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(sel),
1. The smallest unit of living structure capable of independent existence, composed of a membrane-enclosed mass of protoplasm and containing a nucleus or nucleoid. Cells are highly variable and specialized in both structure and function, although all must at some stage replicate proteins and nucleic acids, use energy, and reproduce themselves.
2. A small closed or partly closed cavity; a compartment or hollow receptacle.
3. A container of glass, ceramic, or other solid material within which chemical reactions generating electricity take place or solutions are placed for photometric assays.
[L. cella, a storeroom, a chamber]
(sel)
1. any of the protoplasmic masses making up organized tissue, consisting of a nucleus surrounded by cytoplasm enclosed in a cell or plasma membrane. It is the fundamental, structural, and functional unit of living organisms. In some of the lower forms of life, such as bacteria, a morphological nucleus is absent, although nucleoproteins (and genes) are present.
2. a small, more or less closed space.
accessory cells macrophages involved in the processing and presentation of antigens, making them more immunogenic.
acid cells parietal c's.
acinar cell , acinic cell, acinous cell any of the cells lining an acinus, especially the zymogen-secreting cells of the pancreatic acini.
adventitial cell pericyte.
1. any minute bodily chamber filled with air, such as an alveolus of the lung.
2. a cavity containing air and surrounded by a bodily structure, usually one of the bones of the head, such as the ethmoid or mastoid.
alpha cell
1. a type of cell found in the periphery of the islets of Langerhans that secretes glucagon.
2. acidophil (2).
alveolar cell pneumonocyte; any cell of the walls of the pulmonary alveoli; often restricted to the cells of the alveolar epithelium (squamous alveolar cells and great alveolar cells) and alveolar phagocytes.
Alzheimer cells
1. giant astrocytes with large prominent nuclei found in the brain in hepatolenticular degeneration and hepatic coma.
2. degenerated astrocytes.
amacrine cell any of five types of retinal neurons that seem to lack large axons, having only processes that resemble dendrites.
ameboid cell a cell that shows ameboid movement.
Anichkov's cell a plump modified histiocyte in the inflammatory lesions of the heart (Aschoff bodies) characteristic of rheumatic fever.
APUD cells [a mine p recursor u ptake and d ecarboxylation] a group of cells that manufacture polypeptides and biogenic amines serving as hormones or neurotransmitters. The polypeptide production is linked to the uptake of a precursor amino acid and its decarboxylation to an amine.
argentaffin cells enterochromaffin cells that reduce ammoniacal silver solutions without additional treatment with a reducing agent; the reducing substance is serotonin.
Arias-Stella cells columnar cells in the endometrial epithelium which have a hyperchromatic enlarged nucleus and which appear to be associated with chorionic tissue in an intrauterine or extrauterine site.
Askanazy cells large eosinophilic cells found in the thyroid gland in autoimmune thyroiditis and Hürthle cell tumors.
automatic cell pacemaker c.
B cells B lymphocytes.
band cell a late metamyelocyte in which the nucleus is in the form of a curved or coiled band.
basal cell an early keratinocyte, present in the stratum basale of the epidermis.
basal granular cells APUD cells located at the base of the epithelium at many places in the gastrointestinal tract.
basket cell a neuron of the cerebral cortex whose fibers form a basket-like nest in which a Purkinje cell rests.
beaker cell goblet c.
beta cell
1. a type of basophilic cell that makes up most of the bulk of the islets of Langerhans and secretes insulin.
2. basophil (3).
Betz cells large pyramidal ganglion cells forming a layer of the gray matter of the brain.
bipolar cell a neuron with two processes.
blast cell
1. blast (1).
2. the least differentiated blood cell without commitment as to its particular series; it precedes a stem cell.
blood cell one of the formed elements of the blood; a leukocyte, erythrocyte, or platelet.
bone cell osteocyte.
burr cell schistocyte.
cartilage cell chondrocyte.
CD4 cells a major classification of T lymphocytes, referring to those that carry CD4 antigens; most are helper cells.
CD8 cells a major classification of T lymphocytes, referring to those that carry the CD8 antigen, including cytotoxic T lymphocytes and suppressor cells.
chief cells
1. columnar or cuboidal epithelial cells that line the lower portions of the gastric glands and secrete pepsin.
2. pinealocytes.
3. the most abundant parenchymal cells of the parathyroid, being polygonal epithelial cells rich in glycogen, having granular cytoplasm and vesicular nuclei, and arranged in plates or cords; cf. oxyphil c's.
4. the principal chromaffin cells of the paraganglia, each of which is surrounded by supporting cells.
5. chromophobe c's.
chromaffin cells cells staining readily with chromium salts, especially those of the adrenal medulla and similar cells occurring in widespread accumulations throughout the body in various organs, whose cytoplasm shows fine brown granules when stained with potassium bichromate.
chromophobe cells faintly staining cells in the adenohypophysis; some are nongranular (either nonsecretory, immature presecretory, or degenerating cells), while others have extremely small granules; they are increased in chromophobe adenomas.
Claudius cells cuboidal cells, which along with Böttcher's cells form the floor of the external spiral sulcus, external to the organ of Corti.
columnar cell an elongated epithelial cell.
committed cell a lymphocyte which, after contact with antigen, is obligated to follow an individual course of development leading to antibody synthesis or immunological memory.
cell of Corti a hair cell in the organ of Corti.
cuboidal cell an epithelial cell whose transverse and vertical diameters are approximately equal.
daughter cell one formed by division of a mother cell.
decidual cells connective tissue cells of the uterine mucous membrane, enlarged and specialized during pregnancy.
Deiters cells the outer phalangeal cells of the organ of Corti.
delta cells cells in the pancreatic islets that secrete somatostatin.
dendritic cells cells with long cytoplasmic processes in the lymph nodes and germinal centers of the spleen; such processes, which extend along lymphoid cells, retain antigen molecules for extended periods of time.
dust cell alveolar macrophage.
effector cell any cell, such as an activated lymphocyte or plasma cell, which is instrumental in causing antigen disposal accomplished by either a cell-mediated or a humoral immunological response.
enamel cell ameloblast.
enterochromaffin cells chromaffin cells of the intestinal mucosa that stain with chromium salts and are impregnable with silver; they are sites of synthesis and storage of serotonin.
epithelial cells cells that cover the surface of the body and line its cavities.
epithelioid cells
1. large polyhedral cells of connective tissue origin.
2. highly phagocytic, modified macrophages, resembling epithelial cells, which are characteristic of granulomatous inflammation.
erythroid cells blood cells of the erythrocytic series.
ethmoid cells , ethmoidal cells, ethmoidal air cells ethmoidal sinuses; paranasal sinuses found in groups within the ethmoid bone and communicating with the ethmoidal infundibulum and bulla and the superior and highest meatuses; often subdivided into anterior, middle, and posterior.
eukaryotic cell a cell with a true nucleus; see eukaryote.
excitable cell a cell that can generate an action potential at its membrane in response to depolarization and may transmit an impulse along the membrane.
fat cell a connective tissue cell specialized for the synthesis and storage of fat; such cells are bloated with globules of triglycerides, the nucleus being displaced to one side and the cytoplasm seen as a thin line around the fat droplet.
fat-storing cell of liver lipid-accumulating, stellate cells located in the perisinusoidal space of the liver.
foam cells cells with a vacuolated appearance due to the presence of complex lipids; seen notably in xanthoma.
follicle cells , follicular cells cells located in the epithelium of follicles, such as those of the thyroid or ovarian follicles.
follicular center cell any of a series of B lymphocytes occurring normally in the germinal center and pathologically in the neoplastic nodules of follicular center cell lymphoma; they are believed to be intermediate stages in the development of lymphoblasts and plasma cells and are distinguished according to size (large or small) and the presence or absence of nuclear folds or clefts (cleaved or noncleaved).
G cells granular enterochromaffin cells in the mucosa of the pyloric part of the stomach, a source of gastrin.
ganglion cell a large nerve cell, especially one of those of the spinal ganglia.
Gaucher cell a large cell characteristic of Gaucher's disease, with eccentrically placed nuclei and fine wavy fibrils parallel to the long axis of the cell.
germ cells the cells of an organism whose function it is to reproduce its kind, i.e., oocytes and spermatozoa and their immature stages.
ghost cell
1. a keratinized denucleated cell with an unstained, shadowy center where the nucleus has been.
2. a degenerating or fragmented erythrocyte with no hemoglobin.
giant cell
1. any very large cell, such as the megakaryocyte of bone marrow.
2. any of the very large, multinucleate, modified macrophages, which may be formed by coalescence of epithelioid cells or by nuclear division without cytoplasmic division of monocytes, e.g., those characteristic of granulomatous inflammation and those that form around large foreign bodies.
glial cells neuroglial c's.
globoid cell an abnormal large histiocyte found in large numbers in intracranial tissues in Krabbe's disease.
glomus cell
1. any of the specific cells of the carotid body, which contain many dense-cored vesicles, occurring in clusters surrounded by other cells with no cytoplasmic granules.
2. any of the modified smooth muscle cells surrounding the arterial segment of a glomeriform arteriovenous anastomosis.
goblet cell a unicellular mucous gland found in the epithelium of various mucous membranes, especially that of the respiratory passages and intestines.
Golgi cells see under neuron.
granular cell one containing granules, such as a keratinocyte in the stratum granulosum of the epidermis, when it contains a dense collection of darkly staining granules.
granule cells
1. diminutive cells found in the granular layers of the cerebral and cerebellar cortices.
2. small nerve cells without axons, whose bodies are in the granular layer of the olfactory bulb.
granulosa cells cells surrounding the graafian follicle and forming the stratum granulosum and cumulus oophorus, after ovulation becoming lutein cells.
granulosa-lutein cells lutein cells of the corpus luteum derived from granulosa cells.
gustatory cells taste c's.
hair cells sensory epithelial cells with long hairlike processes (kinocilia or stereocilia) found in the organ of Corti and the vestibular labyrinth.
hairy cell one of the abnormal large leukocytes found in the blood in hairy cell leukemia, having numerous irregular cytoplasmic villi that give the cell a flagellated or hairy appearance.
heart-disease cells , heart-failure cells, heart-lesion cells macrophages containing granules of iron, found in the pulmonary alveoli and sputum in congestive heart failure.
HeLa cells cells of the first continuously cultured carcinoma strain, descended from a human cervical carcinoma.
helmet cell schistocyte.
helper cells , helper T cells differentiated T lymphocytes which cooperate with B lymphocytes in the synthesis of antibody to many antigens; they play an integral role in immunoregulation.
Hensen cells tall supporting cells constituting the outer border of the organ of Corti.
hepatic cells the polyhedral epithelial cells that constitute the substance of an acinus of the liver.
horizontal cell a retinal neuron, occurring in two types, each with one long neurite and several short ones.
Hürthle cells Askanazy c's.
interdental cells cells found in the spiral limbus between the dens acustici, which secrete the tectorial membrane of the cochlear duct.
interstitial cells
1. Leydig c's (1).
2. large epithelioid cells in the ovarian stroma, believed to have a secretory function, derived from the theca interna of atretic ovarian follicles.
3. cells found in the perivascular areas and between the cords of pinealocytes in the pineal body.
4. fat-storing c's of liver.
interstitial cells of Cajal pleomorphic cells having an oval nucleus and long, branching cytoplasmic processes that interlace with processes of adjacent cells, occurring in the gastrointestinal tract and the esophagus; thought to act as pacemakers.
islet cells the alpha and beta cells of the islets of Langerhans.
juxtaglomerular cells specialized cells containing secretory granules, located in the tunica media of the afferent glomerular arterioles, thought to stimulate aldosterone secretion and to play a role in renal autoregulation. These cells secrete the enzyme renin.
K cells
1. killer cells; cells mediating antibody-dependent cell-mediated cytotoxicity; they are small lymphocytes without T or B cell surface markers, having cytotoxic activity against target cells coated with specific IgG antibody.
2. cells in the duodenal and jejunal mucosa that synthesize gastric inhibitory polypeptide.
killer cells
1. K c's (1).
2. cytotoxic T lymphocytes.
Kupffer cells large, stellate or pyramidal, intensely phagocytic cells lining the walls of the hepatic sinusoids and forming part of the reticuloendothelial system.
Kupffer cells lining a hepatic sinusoid.
lacunar cell a variant of the Reed-Sternberg cell, primarily associated with the nodular sclerosis type of Hodgkin's disease.
LAK cells lymphokine-activated killer c's.
Langerhans cells stellate dendritic cells, derived from precursors in the bone marrow, containing characteristic inclusions (Birbeck granules) in the cytoplasm and found principally in the epidermis. They are believed to be antigen-presenting cells involved in cell-mediated immune reactions in the skin.
large cleaved cell see follicular center c.
large noncleaved cell , large uncleaved cell see follicular center c.
LE cell a neutrophil or macrophage that has phagocytized the denatured nuclear material of an injured cell (hematoxylin body); a characteristic of lupus erythematosus, but also found in analogous connective tissue disorders.
Leydig cells
1. clusters of epithelioid cells constituting the endocrine tissue of the testis, which elaborate androgens, chiefly testosterone.
2. mucous cells that do not pour their secretion out over the epithelial surface.
littoral cells flattened cells lining the walls of lymph or blood sinuses.
luteal cells , lutein cells the plump, pale-staining, polyhedral cells of the corpus luteum.
lymph cell lymphocyte.
lymphokine-activated killer cells killer cells activated by interleukin-2 and having specificity for tumors refractory to NK cells.
lymphoid cells lymphocytes and plasma cells; cells of the immune system that react specifically with antigen and elaborate specific cell products.
mast cell a connective tissue cell capable of elaborating basophilic, metachromatic cytoplasmic granules that contain histamine, heparin, hyaluronic acid, slow-reacting substance of anaphylaxis, and, in some species, serotonin.
mastoid cells air cells of various sizes and shapes in the mastoid process of the temporal bone.
Merkel cell a specialized cell at or near the epithelial–dermal junction and believed to act as a touch receptor by association with the flat, disklike ending of a nerve fiber (tactile meniscus).
Mexican hat cell target c. (1).
microglial cell a cell of the microglia.
mother cell one that divides to form new, or daughter, cells.
mucous cells cells which secrete mucus or mucin.
muscle cell see under fiber.
myoid cells cells in the seminiferous tubules which are presumed to be contractile and to be responsible for the rhythmic shallow contractions of the tubules.
natural killer cells NK c's.
nerve cell neuron.
neuroendocrine cells the specialized neurons that secrete neurohormones.
neuroglia cells , neuroglial cells the branching, non-neural cells of the neuroglia; they are of three types: astroglia, oligodendroglia (collectively termed macroglia), and microglia.
neurosecretory cell any cell with neuron-like properties that secretes a biologically active substance acting on another structure, often at a distant site.
nevus cell a small oval or cuboidal cell with a deeply staining nucleus and scanty pale cytoplasm, sometimes containing melanin granules, possibly derived from Schwann cells or embryonal nevoblasts; they are clustered in rounded masses (theques ) in the epidermis, and reach the dermis by a kind of centripetal extrusion.
Niemann-Pick cells Pick c's.
NK cells natural killer cells; cells capable of mediating cytotoxic reactions without themselves being specifically sensitized against the target.
null cells lymphocytes that lack the surface antigens characteristic of B and T lymphocytes; seen in active systemic lupus erythematosus and other disease states.
nurse cells , nursing cells Sertoli c's.
olfactory cells a set of specialized cells of the mucous membranes of the nose, which are receptors of smell.
osteoprogenitor cells relatively undifferentiated cells found on or near all of the free surfaces of bone, which, under certain circumstances, undergo division and transform into osteoblasts or coalesce to give rise to osteoclasts.
oxyntic cells parietal c's.
oxyphil cells , oxyphilic cells
1. acidophilic cells found, along with the more numerous chief cells, in the parathyroid glands.
2. Askanazy c's.
P cells poorly staining, pale, small cells almost devoid of myofibrils, mitochondria, or other organelles; they are clustered in the sinoatrial node, where they are thought to be the center of impulse generation, and in the atrioventricular node.
pacemaker cell a myocardial cell displaying automaticity.
packed red blood cells whole blood from which plasma has been removed; used therapeutically in blood transfusions.
Paget cell , pagetoid cell a large, irregularly shaped, pale anaplastic tumor cell found in the epidermis in Paget's disease of the nipple and in extramammary Paget's disease.
Paneth cells narrow, pyramidal, or columnar epithelial cells with a round or oval nucleus close to the base of the cell, occurring in the fundus of the crypts of Lieberkühn; they contain large secretory granules that may contain peptidase.
parafollicular cells ovoid epithelial cells located in the thyroid follicles; they secrete calcitonin.
parietal cells large spheroidal or pyramidal cells that are the source of gastric hydrochloric acid and are the site of intrinsic factor production.
peptic cells chief c's (1).
peritubular contractile cells myoid c's.
pheochrome cells chromaffin c's.
Pick cells round, oval, or polyhedral cells with foamy, lipid-containing cytoplasm, found in the bone marrow and spleen in Niemann-Pick disease.
pigment cell any cell containing pigment granules.
pillar cells elongated supporting cells in a double row (inner and outer pillar c's) in the organ of Corti, arranged to form the inner tunnel.
Pillar cells forming the inner tunnel in the organ of Corti in the inner ear.
plasma cell spherical or ellipsoidal cells with a single nucleus containing chromatin, an area of perinuclear clearing, and generally abundant, sometimes vacuolated, cytoplasm; they are involved in the synthesis, storage, and release of antibody.
polychromatic cells , polychromatophil cells immature erythrocytes staining with both acid and basic stains in a diffuse mixture of blue-gray and pink.
pre-B cells lymphoid cells that are immature and contain cytoplasmic IgM; they develop into B lymphocytes.
pre-T cell a T lymphocyte precursor before undergoing induction of the maturation process in the thymus; it lacks the characteristics of a mature T lymphocyte.
prickle cell a cell with delicate radiating processes connecting with similar cells, being a dividing keratinocyte of the stratum spinosum (prickle cell layer) of the epidermis.
primordial germ cell the earliest recognizable precursor in the embryo of a germ cell; these originate extragonadally but migrate early in embryonic development to the gonads.
prokaryotic cell a cell without a true nucleus; see prokaryote.
pulmonary epithelial cells extremely thin nonphagocytic squamous cells with flattened nuclei, constituting the outer layer of the alveolar wall in the lungs.
Purkinje's cells
1. large branching neurons in the middle layer of the cerebellar cortex.
2. large, clear, tightly packed, impulse-conducting cells of the cardiac Purkinje fibers.
red cell , red blood cell erythrocyte.
red blood cells official terminology for packed red blood c's.
Reed cells , Reed-Sternberg cells the giant histiocytic cells, typically multinucleate, which are the common histologic characteristic of Hodgkin's disease.
reticular cells the cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen form part of the reticuloendothelial system and may differentiate into macrophages.
reticuloendothelial cell see under system.
Rieder cell see under lymphocyte.
Schwann cell any of the large nucleated cells whose cell membrane spirally enwraps the axons of myelinated peripheral neurons supplying the myelin sheath between two nodes of Ranvier.
segmented cell a mature granulocyte in which the nucleus is divided into definite lobes joined by a filamentous connection.
Sertoli cells cells in the seminiferous tubules to which the spermatids become attached and which support, protect, and apparently nourish the spermatids until they develop into mature spermatozoa.
sickle cell a crescentic or sickle-shaped erythrocyte, characteristic of sickle cell anemia.
small cleaved cell see follicular center c.
small noncleaved cell , small uncleaved cell see follicular center c.
somatic cells the cells of the somatoplasm; undifferentiated body cells.
somatostatin cells endocrine cells of the oxyntic and pyloric glands that secrete somatostatin.
sperm cell spermatozoon.
spur cell acanthocyte.
squamous cell a flat, scalelike type of epithelial cell.
stab cell , staff cell band c.
stellate cell any star-shaped cell, as a Kupffer cell or astrocyte, having many filaments extending in all directions.
stem cell a generalized mother cell that has pluripotency (descendants may specialize in different directions), such as an undifferentiated mesenchymal cell that is a progenitor of both red and white blood cells.
suppressor cells lymphoid cells, especially T lymphocytes, that inhibit humoral and cell-mediated immune responses. They play an integral role in immunoregulation, and are believed to be operative in various autoimmune and other immunological disease states.
synovial cells fibroblasts lying between the cartilaginous fibers in the synovial membrane of a joint.
T cells T lymphocytes.
target cell
1. an abnormally thin erythrocyte that when stained shows a dark center surrounded by a pale unstained ring and a peripheral ring of hemoglobin; seen in certain anemias, thalassemias, hemoglobinopathies, obstructive jaundice, and the postsplenectomy state.
2. any cell selectively affected by a particular agent, such as a hormone or drug.
taste cells cells in the taste buds that have gustatory receptors.
tendon cells flattened cells of connective tissue occurring in rows between the primary bundles of the tendons.
theca cells , theca-lutein cells lutein cells derived from the theca interna of the graafian follicle.
transitional cells
1. cells in the process of changing from one type to another.
2. in the sinoatrial and atrioventricular nodes, small, slow-conducting, heterogeneous cells interposed between the P cells and Purkinje cells.
visual cells the neuroepithelial elements of the retina.
white cell , white blood cell leukocyte.
(sĕl)
1. The smallest structural unit of an organism that is capable of independent functioning, consisting of cytoplasm, usually one nucleus, and various other organelles, all surrounded by a semipermeable cell membrane.
2. A small enclosed cavity or space.
Etymology: L, cella, storeroom
the fundamental unit of all living tissue. Eukaryotic cells consist of a nucleus, cytoplasm, and organelles surrounded by a plasma membrane. Within the nucleus are the nucleolus (containing ribonucleic acid) and the chromatin (containing protein and deoxyribonucleic acid), which form chromosomes, wherein are located the determinants of inherited characteristics. Organelles within the cytoplasm include the endoplasmic reticulum, ribosomes, Golgi apparatus, mitochondria, lysosomes, and centrosome. Prokaryotic cells are much smaller and simpler than eukaryotic cells, even lacking a nucleus. The specialized nature of body tissue reflects the specialized structure and function of its constituent cells. See also cell theory. cellular, adj.
3. A container of glass, ceramic, or other solid material within which chemical reactions that generate electricity occur.
(sel) [L. cella, a chamber]
GENERALIZED HUMAN CELL AND ORGANELLES
The basic unit of life. A cell is a group of self-sustaining biochemical reactions that are isolated from the environment by a selectively permeable lipid membrane. Among the key reactions are those that maintain a stable intracellular concentration of ions; for mammalian cells, typical internal concentrations include 140 mM K+, 5-15 mM Na+, 5-15 mM Cl-, and a pH of 7.2, which can be significantly different from their concentrations outside the cell. Other key reactions move molecules and molecular complexes within the cell, sometimes changing the cell's shape. These reactions, along with many others, require energy, and the generation of energy by breaking apart preexisting hydrocarbon molecules ("food") is the job of glycolysis and other characteristic intracellular metabolic reactions. See: glycolysis; metabolism; mitochondrion.
Intracellular chemical reactions are controlled by enzymes that are organized in stable molecular complexes called organelles. The polymer-based organelles include centrioles and the cytoskeleton; nucleic acid-based organelles include ribosomes; and membrane-enclosed organelles include the nucleus, endoplasmic reticula, Golgi complexes, lysosomes, peroxisomes, mitochondria, and storage and transport vesicles. See: illustrationIndividual mammalian cells are usually microscopic, typically ranging from 5 µm to 50 µm in diameter. In humans, lymphocytes are small cells (~6 µm in diameter), columnar epithelial cells (10 µm x 20 µm) are medium-size cells, and mature ova (120-150 µm) are some of the largest cells.
In mammals, all new cells arise from existing cells through cell division, and an animal's growth results largely from increases in the number of its cells, most of which differentiate into specialized cell types to form the body's various tissues. Cell division involves two major processes: karyokinesis, the division of the nucleus, and cytokinesis, the division of the remainder of the cell. When generating somatic daughter cells, karyokinesis uses a process called mitosis, which produces daughter cells with a full complement of chromosomes. When generating germ cells, karyokinesis includes a process called meiosis, which produces daughter cells with half the normal number of chromosomes. See: meiosis and mitosis for illus.
A cell
Alpha cell of the pancreas.
A monocyte or macrophage that participates in the immune response.
See: antigen-presenting cell; macrophage
acidophilic cell
Acidophil.
acinar cell
A cell present in the acinus of an acinous gland, e.g., of the pancreas.
adipose cell
Adipocyte..
adult stem cell
A precursor cell that can also give rise to identical precursor cells: daughters of a stem cell can develop into a terminally-differentiated cell type or they can remain a stem cell. Adult stem cells are found in many tissues, such as bone marrow, brain, retina, skin, intestines, liver, testis, and pancreas.
Synonym: somatic stem cell See: embryonic stem cell
adventitial cell
A macrophage along a blood vessel, together with perivascular undifferentiated cells associated with it.
An air-filled sinus cavity in a bone.
1. An enteroendocrine cell that produces glucagon and is found in the pancreatic islets. Synonym: A cell
2. An acidophil of the adenohypophysis (anterior pituitary gland).
alveolar cell
1. In the lung, either of two types of epithelial cells lining the alveoli. Type I cells are simple thin squamous epithelial cells. Type II cells secrete pulmonary surfactant. Type II cells are smaller and more numerous than Type I cells.
2. In the mammary glands, the milk-secreting epithelial cells, which are activated during lactation.
amacrine cell
A modified nerve cell in the retina that has dendrites but no axon.
See: neuron
ameloblast cell
Ameloblast.
anterior horn cell
A somatic motor neuron that has its cell body in the ventral (anterior) horn of the gray matter of the spinal cord; its axon passes out through a ventral root and innervates skeletal muscle.
antigen-presenting cell
Abbreviation: APC
A cell that breaks down antigens and displays their fragments on surface receptors next to major histocompatibility complex molecules. This presentation is necessary for some T lymphocytes that are unable to recognize soluble antigens. Macrophages are the primary antigen-presenting cells, but B cells and dendritic cells also can act as APCs.
See: T cell; macrophage processing cell
APUD
The abbreviated name for an 'amine precursor uptake and decarboxylation cell'. These cells are the constituents of a diffuse neuroendocrine system and all have metabolic pathways that make and utilize serotonin (5-HT). APUD cells include chromaffin cells, enterochromaffin cells, and SIF cells as well as certain cells found in the parathyroid gland, thyroid gland, pituitary gland, hypothalamus, and placenta.
argentaffin cell
A cell in the epithelium of the stomach, intestines, and appendix that secretes serotonin.
astroglial cell
Astrocyte.
atypical glandular cells
Abbreviation: AGC
An abnormal finding on a Pap test. This classification is divided into “favor neoplasia” or “not otherwise specified (NOS).” NOS is subdivided into endocervical or endometrial origin. Atypical endocervical cells are important because of their risk for significant disease.
Synonym: atypical glandular cells of undetermined significance
atypical glandular cells of undetermined significance
Abbreviation: AGUS
Atypical glandular cells.
1. A lymphocyte that synthesizes and secretes antibodies. B lymphocytes originate and differentiate in the bone marrow and then populate the spleen, lymph nodes, and other lymphoid tissues. When exposed to an antigen, a B cell divides to form (a) plasma cells, which produce antigen-specific antibodies, and (b) a lesser number of memory B cells, which can quickly differentiate into plasma cells upon a second exposure to the original antigen. Antibody production is a key part of the humoral immune response of adaptive immunity. The humoral immune response is effective against bacteria, viruses, and other pathogens, and provides the rationale for vaccination. Synonym: B lymphocyte See: ; T cell;
2. Pancreatic beta cell.
band cell
The developing leukocyte at a stage at which the nucleus is not segmented.
basal cell
1. A rounded or cuboidal epithelial stem cell found in the bottom layer of pseudostratified epithelia, such as the epidermis and the lining of the airways of the lung.
2. Either of two types of cell found in the bottom layer of the olfactory epithelium; one type is a flattened "basal cell proper", and the other is a rounded stem cell called a globose cell.
3. A rounded stem cell found in the taste buds and a progenitor of the specialized taste receptor cells.
basket cell
1. Myoepithelial cell.
2. One of the nonspiny granule cells found in the cerebral cortex.
3. One of the small interneurons found in the outermost layer of the cerebellar cortex along with stellate cells.
basophilic cell
Basophil.
1. Any of the insulin-secreting cells of the pancreas that constitute the bulk of the islets of Langerhans. Synonym: B cell
2. A basophil cell of the adenohypophysis (anterior pituitary gland).
Betz cell
See: Betz cells
Bipolar neuron.
1. A precursor cell for a specific cell type.
2. An immature cell of a specific type.
Any cell normally found circulating in the blood stream. Blood cells include red cells and white cells; red cells generally remain inside blood vessels, while white cells can also more into the tissues outside the blood vessel walls.
See: blood for illus.
bone cell
An osteoblast, osteoclast, or osteocyte.
bone marrow cell
Marrow cell.
brush cell
An epithelial cell found sparsely in the lining of the bronchial tree. The cell's surface has long stiff microvilli, and the cell has the appearance of an absorptive cell.
An erythrocyte with 10 to 30 spicules distributed over the surface of the cell, as seen in heart disease, stomach cancer, kidney disease, and dehydration. Synonym: echinocyte
A cell present in a neoplasm and differentiated from normal tissue cells because of its degree of anaplasia, irregularity of shape, nuclear size, changes in the structure of the nucleus and cytoplasm, increased number of mitoses, and ability to metastasize.
capsule cell
Satellite cell.
cartilage cell
Chondrocyte.
castration cell
An enlarged and vacuolated basophil cell seen in the pituitary in gonadal insufficiency or following castration.
CD3 cell
T cell.
Helper T cell.
A suppressor T cell, e.g., a cytotoxic T cell.
CD 34+ cell
A cell with the CD34 protein on its surface membrane. Some CD34 cells that are hemopoietic stem cells can be separated out from peripheral blood.
cementoblast cell
Cementoblast.
cementocyte cell
Any of the cells trapped within cementum that maintain cementum as a living calcified tissue by their metabolic activity.
centroacinar cell
A duct cell of the pancreas more or less invaginated into the lumen of an acinus.
chalice cell
Goblet cell.
chemoreceptor cell
Chemoreceptor.
chief cell
1. Any of the cells of the parathyroid gland that secretes the parathyroid hormone.
2. Any of the cells of the gastric glands that secretes pepsinogen.
chromaffin cell
A cell that produces, stores, and secretes catecholamines (dopamine and norepinephrine). Chromaffin cells are found in the medulla of the adrenal glands and in small clusters in the sympathetic ganglia.
chromophobe cell
Chromophobe.
Clara cell
A cuboidal epithelial cell found in the lining of the terminal and the respiratory bronchioles of the lungs. Clara cells are nonciliated, and they secrete surfactant, like the type II alveolar epithelial cells found deeper in the bronchial tree.
cleavage cell
Blastomere.
clue cell
A vaginal epithelial cell, thickly coated with coccobacillary organisms. Clue cells are a hallmark of bacterial vaginosis.
columnar cell
An epithelial cell with height greater than its width.
columnar epithelial cell
Columnar cell.
cone cell
A cell in the retina whose scleral end forms a cone that serves as a light receptor. Vision in bright light, color vision, and acute vision depend on the function of the cones. See: rod cell
contrasuppressor cell
A T cell that inhibits the activity of suppressor T cells. Although a contrasuppressor cell shares this functional capability with T helper cells, it is distinguished from other CD4+ cells by its other cell surface markers and the unique group of cytokines it produces.
cortical cell
A cell in the cortex of an organ, e.g., a neuron in the cerebral cortex.
corticotroph cell
Corticotroph.
cuboid cell
A cell – usually epithelial – with a height about equal to its width and depth.
cytotoxic cell
Cytotoxic T cell.
cytotoxic T cell
A CD8+ T lymphocyte that can destroy microorganisms directly through the release of perforin and proteolytic enzymes. These cells are particularly important in the defense against viruses, rejection of allografts, and, possibly, new malignant cells. Synonym: CD8 cell; cytotoxic cel; killer T cell
D cell
An enteroendocrine cell that produces somatostatin and is found in the pancreatic islets, stomach, and small intestine. Synonym: delta cell; somatostatin cell
daughter cell
A cell formed by cell division.
decoy cell
A cell found in the urine with inclusion bodies in its nucleus. It indicates infection with BK virus in renal transplant recipients.
delta cell
Pancreatic D cell.
One type of antigen-presenting cell that helps T cells respond to foreign antigens. Dendritic cells are found in epithelial tissues and include the Langerhans' cells of the skin and the interdigitating cells in lymph nodes; they also circulate in the blood.
Downey cell
See: Downey cell
dust cell
A macrophage that migrates into the lumen of lung aveoli and ingests debris, particles of air pollution, and pathogens to keep the airspaces clear.
EC cell
1. An embryonal carcinoma cell, which is a cultured cell line.
2. An enterochromaffin cell that secretes substance P and is found in the stomach and small intestine.
A cell that carries out the final response or function of a particular process. The main effector cells of the immune system, for example, are activated lymphocytes and phagocytes—the cells involved in destroying pathogens and removing them from the body.
See: leukocyte
embryonic stem cell
Abbreviation: ES cell
A cell from the inner cell mass of the blastocyst (the 3-5 day old mammalian embryo) that can give rise to all the somatic cells of the body. Embryonic stem cells can be maintained as pure stem cell cultures.
See: adult stem cell
endothelial cell
The type of epithelial cell that lines blood vessels and lymph vessels; these cells are usually squamous (flattened) and form sheets one layer thick. Endothelial cells are derived from mesenchyme cells of the embryo. A sheet of endothelial cells is called an endothelium.
See: endothelium
enterochromaffin cell
Abbreviation: EC cell
An enteroendocrine cell that produces serotonin and is found in the small intestine. Enterochromaffin cells are very similar to the cells, found throughout the peripheral sympathetic nervous system, that are called simply 'chromaffin cells'.
enteroendocrine cell
One of the scattered hormone-producing cells found in the pancreatic islets and throughout the gastrointestinal (mainly, small intestinal) mucosa.
ependymal cell
Any of the epithelial cells that form a one-cell-thick layer lining the ventricles and the central canal of the central nervous system. The ventricular (apical) surfaces of many ependymal cells are covered with cilia or microvilli. In most places, the ependymal layer does not have a basal lamina. Specialized regions of ependymal cells include the covering of the blood vessels and loose connective tissue of the choroid plexuses; here, the ependyma is specialized to secrete cerebrospinal fluid.
epithelial cell
Any of the cells forming the cellular sheets that cover surfaces, both inside and outside the body. Epithelial cells are closely packed and take on polyhedral shapes, from tall (columnar) through squat (cuboidal) to flat (squamous). Epithelial cells adhere strongly to one another, and one of their surfaces -- the basal surface -- sticks firmly to a thin extracellular film of fibrils called a basal lamina. A sheet of epithelial cells derived from embryonic epithelia (the ectoderm or the endoderm) is called an epithelium. See: epithelium
ethmoidcell
Ethmoid sinus.
eukaryotic cell
The type of cell composing multicellular, as well as a number of unicellular, organisms. Unlike prokaryotic cells, eukaryotic cells have many of their intracellular functions organized within structures called organelles. Some organelles -- notably, the nucleus, which contains the DNA -- are enclosed by intracellular membranes.
F cell
An enteroendocrine cell that produces pancreatic polypeptide and is found in the pancreatic islets.
fat cell
Adipocyte.
flame cell
A bone marrow cell with a bright red cytoplasm, occasionally found in the marrow of patients with multiple myeloma.
An optical cell used in photometers and cell counters, through which the sample and any standards are passed for detection and measured or counted by optical or electrometric means.
See: cytometry
foam cell
A cell that contains vacuoles; a lipid-filled macrophage.
follicle cell
Follicular cell.
follicular cell
1. The secretory cell of the thyroid gland; it produces the thyroid hormones, T3 (triiodothyronine) and T4 (tetraiodothyronine or thyroxine).
2. Any of the flattened somatic cells that form a monolayer around each primary oocyte in the ovary. After puberty, when an oocyte matures, during a monthly cycle, its follicular cells divide, become cuboidal, and form a multilayered coating for the oocyte; at this stage, the follicular cells are called granulosa cells.
folliculostellate cell
A supporting cell in the adenohypophysis (anterior pituitary gland); it produces bioactive peptides, including growth factors and cytokines.
foreign body giant cell
Giant cell.
G cell
An enteroendocrine cell found in the stomach that produces the hormone gastrin.
ganglion cell
1. Any neuron whose cell body is located within a ganglion.
2. A neuron of the retina of the eye whose cell body lies in the ganglion cell layer. The axons of ganglion cells form the optic nerve.
germ cell
A cell whose function is to reproduce the organism. Early in development, primordial germ cells are found in the genital ridges of the embryo. Later, in the testis, the primordial germ cells are called spermatogonia, and in the ovary, they are called oogonia. When they mature, the germ cells (i.e., spermatogonia and oogonia) differentiate into haploid gametes (i.e., spermatozoa and ova).
Synonym: primordial germ cell
1. A multinucleated phagocyte created by several individual macrophages that have merged around a large pathogen or a substance resistant to destruction, such as a splinter or surgical suture. See: granuloma; tuberculosis
2. A large multinucleated (40-60 nuclei) tumor cell characteristic of certain bone and tendon tumors.
3. A large multinucleated cell that invades the walls of the aorta and its major branches in giant cell arteritis.
One of three types of nonneuronal cell in the central nervous system: astrocytes, oligodendrocytes, and microglial cells. SYN neuroglial cell
Synonym: neuroglial cell
gitter cell
A macrophage present at sites of brain injury. The cells are packed with lipoid granules from phagocytosis of damaged brain cells.
See: microglia
globus cell
One of the two varieties of basal cell found in the olfactory epithelium. It is a rounded neuroblast or neural stem cell for the olfactory receptor cells.
goblet cell
A mucous cell sitting between nonsecretory cells, such as is found in the intestinal epithelium.
Golgi cell
See: Golgi, Camillo
gonadotroph cell
Gonadotroph.
graft facilitating cell
Any of a group of CD8 positive, t-cell receptor negative cells that help donated bone marrow engraft in the recipient.
granule cell
1. Any of the small neurons that pack the granular cell layer of the cerebellar cortex, immediately below the Purkinje cell layer. Granule cells receive inputs (mossy fibers) from the spinal cord and brainstem (except the inferior olive). Axons of granule cells run perpendicular to the Purkinje cell dendrites, on which they synapse.
2. Any of the neurons of the cerebral cortex that are not pyramidal cells. Cortical granule cells are categorized as spiny or nonspiny. Synonym: stellate cell
3. A small axon-less neuron found in the olfactory bulb.
granulosa cell
One of the many cuboidal cells that surround and nurture the maturing oocyte.
See: follicular cell (2)
gustatory cell
Taste cell.
hair cell
An epithelial cell possessing stereocilia in the maculae, cristae ampullaris, and the organ of Corti. These cells are receptors for the senses of position and hearing.
heart failure cell
A red-colored (from ingested red cells) lung macrophage often found in the sputum of patients with congestive heart failure.
HeLa cell
A line of human epithelial cells that grows well in culture. It is an immortal cancer cell that has been maintained in continuous tissue cultures for decades from a patient with carcinoma of the cervix. It is named for the first two letters of the patient's first and last names, Henrietta Lacks. HeLa cells have been used in thousands of experiments on cell growth, differentiation, and cancer, and in virology, pharmacology, and other fields.
HELMET CELLS: (Orig. mag. ×640)
helmet cell
A schistocyte or fragmented blood cell, seen in hemolytic anemias.
See: illustration
helper cell
A type of T lymphocyte whose surface is marked by CD4 receptors; it is involved in both cell-mediated and antibody-mediated immune responses. It secretes cytokines that stimulate the activity of B cells and other T cells and binds with class II histocompatibility antigens, which are processed by macrophages and other antigen-presenting cells. Synonym: helper T cell See: antigen processing; T cell; cell-mediated immunity
helper T cell
Helper cell.
hematopoietic stem cell
A progenitor cell in the bone marrow that can replicate itself as well as produce precursor cells of the various blood cell lineages.
hilus cell
An androgen-producing cell found in the ovarian hilum. It is analogous to the male Leydig cell.
holly leaf cell
A cell found in blood smears of persons with sickle cell anemia.
horizontal cell
A neuron of the inner nuclear layer of the retina. The axons of these cells run horizontally and connect various parts of the retina.
Hürthle cell
See: Hürthle cell
hybridoma cell
See: hybridoma
hyperchromatic cell
A cell that contains more than the normal number of chromosomes and hence stains more densely.
I cell
An enteroendocrine cell that produces the enzyme cholecystokinin-pancreozymin (pancreaticozymin) and is found in the small intestine.
interdigitating cell
A type of antigen-presenting cell found in lymph nodes and lymphoid tissue.
interstitial cell
Any of the many cells found in connective tissue of the ovary, in the seminiferous tubules of the testes, and in the medulla and cortex of the kidney. The cells in the testes and ovaries produce hormones such as testosterone and estrogen.
intestinal absorptive cell
In the small intestine, any of the tall columnar cells topped with a brush border made of thousands of microvilli.
islet cell
A cell of the islets of Langerhans of the pancreas.
juvenile cell
The early developmental form of a leukocyte.
juxtaglomerular cell
A modified smooth muscle cell in the wall of the afferent arteriole leading to a glomerulus of the kidney. This type of cell secretes renin when blood pressure decreases to activate the renin-angiotensin mechanism, which increases sodium retention, thus elevating the blood pressure.
K cell
An enteroendocrine cell that produces gastric inhibitory peptide (glucose-dependent insulinotropic peptide) and is found in the small intestine. This peptide stimulates the beta cells of the pancreas to secrete insulin.
killer cell
Natural killer cell.
killer T cell
Kulchitsky cell
An APUD cell found in the lung.
Kupffer cell
See: Kupffer cell
An enteroendocrine cell that produces glucagon-like peptide-1 and is found in the small intestine. This peptide signals the pancreas to secrete insulin after a meal.
labile cell
A cell that is always mitotically active, such as the epithelial cells lining the stomach and the stem cells in the red bone marrow.
lactotroph cell
Lactotroph.
LAK cell
Abbreviation for lymphokine-activated killer cell. These natural killer cells, obtained from the patient's blood, have been activated in culture with interleukin-2.LAK cells; the cells can then be used to treat patients with solid malignant tumors.
Langerhanscell
A type of dendritic antigen-presenting cell that typically resides in the skin.
L.E. CELL (center): (Orig. mag. ×1000)
L.E. cell
Historically, an abbreviation for lupus erythematosus cell, a polymorphonuclear leukocyte that contains the phagocytized nucleus of another cell. It is characteristic but not diagnostic of lupus erythematosus.
This distinctive cell may form when the blood of patients with systemic lupus erythematosus is incubated and further processed according to a specified protocol. The plasma of some patients contains an antibody to the nucleoprotein of leukocytes. These altered nuclei, which are swollen, pink, and homogeneous, are ingested by phagocytes. These are the L.E. cells. The ingested material, when stained properly, is lavender and displaces the nucleus of the phagocyte to the inner surface of the cell membrane. The L.E. cell phenomenon can be demonstrated in most patients with systemic lupus erythematosus but is not essential for diagnosis.
Leydig cell
See: Leydig's cell
littoral cell
A macrophage found in the sinuses of lymphatic tissue.
liver cell
Hepatocyte.
lutein cell
A cell of the corpus luteum of the ovary that contains fatty yellowish granules. Granulose lutein cells are hypertrophied follicle cells; these lutein (paralutein) cells develop from the theca interna.
lymphoid cell
An obsolete term for lymphocyte.
lymphokine-activated killer cell
LAK cell.
M cell
1. A microfold cell, which is a cell in the gastrointestinal epithelium covering patches of lymphoid tissue. M cells transport antigens from the intestinal lumen to the underlying lymphoid tissues for recognition and processing.
2. An APUD cell that produces melanotropin and is found in the pituitary gland.
macroglial cell
An astrocyte or an oligodendrocyte.
marrow cell
Bone marrow cell.
A large tissue cell resembling a basophil, which is essential for inflammatory reactions mediated by immunoglobulin E (IgE) but does not circulate in the blood. Mast cells are present throughout the body in connective tissue, but are concentrated beneath the skin and the mucous membranes of the respiratory and digestive tracts. Mast cells are covered with IgE molecules, which bind with foreign antigens and stimulate degranulation, releasing such mediators as histamine, prostaglandins, leukotrienes, and proteinases from densely packed granules within the cytoplasm. These mediators produce type I (immediate) hypersensitivity reactions (e.g., urticaria, allergic rhinitis, asthma, angioedema, and systemic anaphylaxis). See: illustration
mastoid cell
Mastoid air cell.
mastoid air cell
Any of the variable-sized, air-filled sinuses inside the mastoid antrum. About 20% of adult skulls have no mastoid air cells.
matrix stem cell
A stem cell derived from Wharton's jelly.
memory cell
A cell derived from B or T lymphocytes that can quickly recognize a foreign antigen to which the body has been previously exposed. Memory T cells stimulate T helper lymphocytes and cytotoxic T cells; memory B cells stimulate the production of antigen-specific antibodies by B plasma cells. Both types of memory cells survive for years, providing a durable adaptive immune response against foreign antigens.
mesenchyme cell
One of the two basic somatic cell lineages -- the other being epithelial cells. In contrast to epithelial cells, mesenchyme cells are not polarized and are frequently motile. In the early embryo, mesenchyme cells fill many of the spaces enclosed by epithelia. Later, mesenchyme cells will secrete the space-filling extracellular matrix molecules, such as collagen and glycoproteins, that characterize connective tissue.
mesenchymal stem cell
A stem cell found in connective tissue and capable of producing cells of the connective tissue lineages, such as cartilage, bone, muscle, and fat cells.
mesothelial cell
The type of epithelial cell that lines serous (pleural, peritoneal, and pericardial) cavities, blood vessels, and lymph vessels; these cells are usually squamous (flattened) and form sheets one layer thick. Mesothelial cells are derived from mesenchyme cells of the embryo. A sheet of mesothelial cells is called a mesothelium.
See: mesothelium
microglial cell
A small glial cell of the central nervous system and retina. Microglia have spiky branched processes and are arranged homogeneously throughout the brain and spinal cord. They are activated by disease and injury, after which they become phagocytic and sometimes resume their embryonic motility like a macrophage.
mitral cell
One of the two principal neurons of the olfactory bulb -- the other being the tufted cell. In a complex synaptic formation called a glomerulus, each of the mitral and tufted cells receives synaptic inputs from axons of the olfactory nerve. The axons of the mitral and tufted cells form the olfactory tract and synapse in the olfactory cortex.
mossy cell
An astrocyte or other glial cell with many branching processes. See: neuroglia
mother cell
A cell that gives rise to similar cells through fission or budding. Synonym: parent cell
mucosal cell
Any cell in a mucosal epithelium.
mucous cell
An epithelial cell that secretes mucus and IgA antibodies. Mucous cells and serous cells are the two varieties of secretory cells found in exocrine glands.
Synonym: mucus cell
mucus cell
Mucous cell.
multinucleated giant cell
multipolar cell
Multipolar neuron.
muscle cell
See: muscle
myeloid cell
Any white blood cell other than lymphocytes.
myeloma cell
A cell present in the bone marrow of patients with multiple myeloma.
myoepithelial cell
A smooth muscle cell found in some epithelia; it lies between glandular cells and the basal lamina of sweat, mammary, lacrimal, and salivary glands.
Synonym: basket cell
Abbreviation: NK cell
A large granular lymphocyte – a defensive cell of innate immunity – that bonds to cells and lyses them by releasing cytotoxins. Natural killer cells are null cells, lymphocytes that do not have B cell or T cell surface markers, and they can be activated without previous antigen exposure. NK cells destroy cells infected with viruses and some types of tumor cells in cultures. They also secrete gamma interferon (INF?), tumor necrosis factor alpha (TNFa), and granulocyte-macrophage colony-stimulating factor (GMCSF), enhancing the effect of T lymphocytes.
Synonym: killer cell
Neuron.
neural crest cell
Embryonic cells of the neuron-glia lineage that form along the ridges (neural folds) of the neural plate and that migrate into the developing organism to produce a variety of tissues. The migratory ability of these embryonic epithelial cells is similar to the motility of mesenchyme cells; this has led neural crest cells to be called mesectodermal cells. In the neural lineage, neural crest cells give rise to the dorsal root ganglia, the placodes that will develop into the olfactory and auditory sensory organs, the pituitary gland, the peripheral autonomic nervous system, and the neurenteric and APUD cells. In the glial lineage, neural crest cells give rise to Schwann cells and other peripheral satellite cells. In addition, neural crest cells of the cranial region give rise to certain facial connective tissue, including the bones of the nasal cavities, the roof of the mouth, and the sella turcica.
neuroglial cell
Glial cell.
Niemann-Pick cell
See: Niemann-Pick cell
NK cell
Any cell found in the bone marrow that cannot reconstitute the marrow or give rise to more differentiated blood cells.
null cell
A large lymphocyte without the cell markers of either a T cell or a B cell. Natural killer cells are examples of null cells.
odontoblast cell
Odontoblast.
oligodendroglial cell
Oligodendrocyte.
olfactory cell
Olfactory receptor cell.
olfactory receptor cell
A cell of the olfactory mucosa that has receptors for the sense of smell. Olfactory cells are continuously replaced from stem cells throughout adult life.
Synonym: olfactory cell
osteoprogenitor cell
Any of the mesenchyme precursor cells committed to the bone lineage and capable of producing osteoblasts and osteocytes. Osteoprogenitor cells are found in bone, bone marrow, and other connective tissue.
oxyntic cell
A parietal cell of the gastric glands; it produces hydrochloric acid and the intrinsic factor.
parabasal cell
An abnormal but not malignant cell seen in some cytologic specimens obtained during Papanicolaou tests (Pap tests). It is found in women with vaginal atrophy, in some postpartum women, some women suffering from anorexia or starvation, and some who have used progesterone for contraception.
parent cell
Mother cell.
phalangeal cell
One of the cells supporting the hair cells of the organ of Corti. These cells form several rows of outer phalangeal cells (Deiters' cells) and a single row of inner phalangeal cells.
phantom cell
See: red cell ghost
pigment cell
Any cell that normally contains pigment granules.
plasma cell
A cell derived from a B lymphocyte that has been sensitized to a specific foreign antigen and produces antibodies to that particular antigen. It may be found in the blood or in tissue fluid. Synonym: plasmacyte
postganglionic cell
Postganglionic neuron.
PP cell
An enteroendocrine endocrine cell found in the pancreatic islets that produces pancreatic polypeptide.
pre-B cell
The immediate precursor of a lymphocytic B cell.
preganglionic cell
Preganglionic neuron.
prickle cell
A cell with spiny processes that connect with similar processes of adjoining cells. These are found in the stratum spinosum of the keratinized epithelium of the epidermis.
In physical therapy, a device consisting of a container, two solid conducting elements, and an electrolyte for the production of electric current by chemical energy.
primordial cell
Primordial germ cell.
primordial germ cell
A germ cell before it begins its maturation into a haploid gamete.
Synonym: primordial cell
progenitor cell
A cell (sometimes a stem cell) that produces cells of a particular lineage, e.g., a neuroblast.
prokaryotic cell
The form of cell composing many primitive unicellular organisms, such as bacteria. Prokaryotic cells do not have nuclei, which are partitioned by an intracellular membrane; instead the DNA forms one main coil in the cell cytoplasm.
See: Purkinje, Johannes E. von
pus cell
A leukocyte present in pus. Pus cells are often degenerated or necrotic.
pyramidal cell
A large, common neuron found in the cerebral cortex. Pyramidal cells are flask-shaped or triangular, and, in the parts of the cortex with six layers, they occupy the fifth layer. Pyramidal cell dendrites project up into the most superficial layer of the cortex, while pyramidal cell axons run in the opposite direction, i.e., downward and out of the cortex.
Synonym: pyramidal neuron
radial glial cell
A structural macroglial cell that is a key component of the developing nervous system. Radial glial cells first appear in the neural tube, where their cell bodies are suspended between two thin cell processes; the apical process attaches to the inner (ventricular) surface of the neural tube, and the basal process attaches to the outer (pial) surface. Early in development, neuroblasts migrate radially along the scaffolding formed by the radial glial cell processes, and growing axons may follow the scaffolding longitudinally. Later, many radial glial cells retract their processes and differentiate into astrocytes.
A small cell that is filled with hemoglobin, has no nucleus, and is shaped like a biconcave disc. Red cells transport oxygen to tissues and carbon dioxide to the lungs. Individual red cells have a life span of 3-4 months, and new red cells are continually being produced in the bone marrow. In a healthy person, 99% of the cells circulating in the blood are red cells.
Synonym: erythrocyte; red blood cell; red blood corpuscle See: erythrocyte
Abbreviation: RBC
Red cell.
Renshaw cell
See: Renshaw cell
resting cell
1. A cell that is not dividing. See: interphase
2. A cell not performing its normal function (i.e., a nerve cell that is not conducting an impulse or a muscle cell that is not contracting).
reticular cell
1. An undifferentiated cell of the spleen, bone marrow, or lymphatic tissue that can develop into one of several types of connective tissue cells or into a macrophage.
2. A cell of reticular connective tissue. See: reticular tissue
reticuloendothelial cell
An out-of-date term for a cell of the mononuclear phagocytic system.
Rieder cell
See: Rieder cell
rod cell
A cell in the retina of the eye whose scleral end is long and narrow, forming a rod-shaped sensory receptor. Rods are stimulated by light and are essential for vision in dim light. See: cone cell
rosette cell
A rose-shaped cluster of phagocytes surrounding lysed nuclear material or red blood cells. Rosette cells occur frequently in blood in which L.E. cells are present. Rosette cells are not diagnostic of lupus erythematosus. See: L.E. cell
Rouget cell
See: Rouget cell
S cell
An enteroendocrine cell that produces secretin and is found in the small intestine.
satellite cell
1. A stem cell associated with skeletal muscle that may form a limited number of new muscle cells after injury.
2. One of the neuroglia cells enclosing the cell bodies of sensory neurons in spinal ganglia. Synonym: capsule cell
scavenger cell
A phagocyte that cleans up disintegrating tissues or cells.
Schwann cell
See: Schwann cell
segmented cell
A segmented neutrophil (i.e., one with a nucleus of two or more lobes connected by slender filaments).
selenoid cell
sensory cell
A cell that when stimulated gives rise to nerve impulses that are conveyed to the central nervous system.
septal cell
A type II alveolar cell that secretes pulmonary surfactant; it is adjacent to a septum of the alveoli.
serous cell
An epithelial cell that secretes a watery fluid containing proteins, glycoproteins, and often antibodies (IgA, IgG, and IgM). Serous cells and mucous cells are the two varieties of secretory cells found in exocrine glands.
Sertoli cell
See: Sertoli cell
sex cell
Gamete.
SICKLED CELLS IN SICKLE CELL DISEASE
sickle cell
An abnormal erythrocyte shaped like a sickle. Synonym: drepanocyte See: anemia, sickle cell
signet-ring cell
A vacuolated cell with the nucleus off center. Mucus-secreting adenocarcinomas usually contain these cells.
skeletal muscle cell
smooth muscle cell
somatic cell
Any cell that is not a germ cell.
somatic stem cell
Adult stem cell.
somatostatin cell
D cell.
spiculed red cell
Crenated red blood cells with surface projections. In most instances, this is a normal variation in red cell equilibrium and is reversible.
See: acanthocyte
spider cell
squamous cell
A flat epithelial cell.
Synonym: squamous epithelial cell
squamous epithelial cell
Squamous cell.
stellate cell
1. Granule cell of the cerebral cortex.
2. One of the small interneurons found in the outer layer of the cerebellar cortex along with basket cells.
stellate reticuloendothelial cell
A Kupffer cell, one of the macrophages that line the sinusoids of the liver.
An embryonic stem cell or an adult stem cell.
Sternberg-Reed cell
See: Reed-Sternberg cell
stipple cell
A red blood cell that contains small basophilic-staining dots. It is seen in lead poisoning, malaria, severe anemia, and leukemia.
striated muscle
suppressor T cell
A subpopulation of regulatory T lymphocytes that develop in the thymus gland, that slows or stops a specific immune response.
sustentacular cell
A supporting cell, as in the acoustic macula, organ of Corti, olfactory epithelium, taste buds, or testes.
sympathicotrophic cell
One of the large epithelial cells that occur in groups in the hilus of the ovary. They are thought to be chromaffin cells.
sympathochromaffin cell
A chromaffin cell of ectodermal origin present in the fetal adrenal gland. Sympathetic and medullary cells originate from these cells.
syncytial giant cell
T cell
A lymphocyte that responds to specific antigens, with the assistance of antigen-presenting cells (APCs). T cells arise in the bone marrow and migrate to the thymus gland, where they mature; then they circulate between blood and lymph, serving as one of the primary cells of the adaptive immune response. Immature T cells are called thymocytes. Mature T cells are antigen specific. Their surface receptors (T cell receptors, abbrev. TCRs) respond only to a single antigen. T cells are further categorized using another family of surface protein markers called clusters of differentiation (CDs). All T cells have a CD3 marker. Additional markers differentiate the subclasses of T cells. CD4 T helper cells serve primarily as regulators, secreting cytokines that stimulate the activities of other white blood cells. CD8 T cells (cytotoxic T cells) directly lyse (kill) organisms, an important defense against viruses; most CD8 T cells also produce gamma interferon (INF?), one of the strongest stimulators of macrophage activity. Synonym: T lymphocyte See: immune response; lymphocyte; immunological surveillance; T-cell receptor
A T cell can only recognize the "foreignness" of antigens after they have been modified by macrophages and other antigen-presenting cells (APCs). After this, T cells dominate the adaptive immune response by mobilizing B cells and other T cells of the cell-mediated immune pathways. T cells are responsible for type IV hypersensitivity reactions, such as graft rejection, and for tumor cell recognition and destruction.
See: cytokine; cell-mediated immunity
TARGET CELLS: In hemoglobin C disease (×600)
1. . An erythrocyte with a dark rounded central area surrounded by a lightly stained clear ring, which in turn is surrounded by a dense ring of peripheral cytoplasm. It is present in certain blood disorders, such as thalassemia, and in patients who have no spleen. See: hemoglobin C disease for illus Synonym: codocyte; leptocyte
2. . The cell at which a signal (e.g., hormone or nerve impulse) is aimed.
tart cell
A phagocyte that has ingested the unaltered nuclei of cells. These nuclei can be observed unchanged within the phagocytes.
taste cell
Any of the neuroepithelial cells within a taste bud that are receptors for the sense of taste. Each possesses on the free surface a short gustatory hair that projects through the inner taste pore.
Synonym: taste receptor cell
taste receptor cell
tear-drop cell
An abnormally shaped blood cell, sometimes found on blood smears of patients with bone marrow fibrosis, iron deficiency, or thalassemias.
Synonym: dacrocyte
tendon cell
Any of the fibroblasts of white fibrous connective tissue of tendons arranged in parallel rows.
terminally differentiated cell
A cell sufficiently committed to a particular function that it can no longer divide, e.g. a red cell.
thymic epithelial cell
The epithelial cells that form the internal scaffolding of the thymus. These cells vary in shape and size but generally align in sheets and cords, partitioning the thymus into islands of close-packed lymphocytes in the organ's cortex. Thymic epithelial cells are not simply structural and they interact actively with adjacent lymphocytes.
thymus cell
Any cell characteristic of the thymus, including thymic epithelial cells and thymocytes (thymic lymphocytes).
thyroid cell
Any cell characteristic of the thyroid gland, but usually referring to a thyroid follicular cell.
totipotent cell
An undifferentiated embryonic cell that has the potential to develop into any type of cell.
Touton giant cell
See: Touton cell
transitional cell
The stretchable epithelial cells that compose the transitional epithelium (uroepithelium), which lines most of the urinary tract. Transitional cells are strongly interconnected. They are cuboidal when not under pressure, and they become flattened and squamous when stretched. Transitional epithelia are 4-6 cells thick, and the top transitional cells -- those on the lumenal surface -- fuse to become larger and polyploid.
trophoblast cell
One of the epithelial cells forming the surface of the spherical blastocyst stage embryo. Trophoblast cells are destined to give rise to many of the extraembryonic tissues.
See: mitral cell
Türk irritation cell
See: Türk irritation cell
Tzanck cell
See: Tzanck cell
undifferentiated cell
A cell resembling an embryonic cell in that it does not have the specific morphologic or functional characteristics of any particular adult cell type.
unipolar cell
A cell with a single cell process.
Vero cell
A lineage of cells used in cell cultures and isolated from kidney epithelial cells of the African green monkey (Cercopithecus aethiops).
visual cell
A rod cell or cone cell of the retina.
wandering cell
A rarely used term for a cell (such as a macrophage) that moves like an ameba.
white cell
Leukocyte.
The structural unit of the body and of all living things, whether plant or animal. Body cells vary in size from one hundredth of a millimetre to about a tenth of a millimetre, in the case of the OVUM. They are structurally complex and are engaged in constant physical, biochemical and genetic activity. The outer cell membrane contains specialized sites for the receipt of chemical information from the external environment and other receptors for the pumping of dissolved substances into and out of the cell. The central nucleus contains the chromatin—the DNA genetic blueprint for the reproduction of the cell and for the synthesis of enzymes. Surrounding the nucleus is the cytoplasm. This contains many important structures (organelles), such as the MITOCHONDRIA (tiny bags containing enzymes needed for the metabolic processes of the cell and for the conversion of glucose and oxygen into energy) and the RIBOSOMES in which proteins are formed.
the structural unit of most organisms, consisting of a microscopic mass of protoplasm bounded by a semi-permeable membrane and usually containing one nucleus (in EUKARYOTES) or chromosomal material not enclosed in a nucleus (in PROKARYOTES). In prokaryotes the cytoplasm is not differentiated into specialized organelles as it is in eukaryotes. Cell size is roughly constant in all tissues and organisms, being limited by the physical restraints of unfavourable surface area/volume ratios as size increases; however, some cells are much larger, for example egg cells, neurone cells. Some organisms consist of single cells; others of many cells of different types. In plants, fungi and bacteria there is a non-living cell-wall.
The smallest living units of the body which group together to form tissues and help the body perform specific functions.
Mentioned in: Cholesterol-Reducing Drugs, Gene Therapy, Wilson Disease
A typical cell and a part of its plasma membrane.
the basic structural unit of living organisms. A human body would typically have ∼1014 cells of different types, ranging in diameter from about 1 to 100 microns. The outer cell membrane ( syn plasma membrane) is a double layer of lipid with embedded protein molecules. These include: molecules that embody enzymes involved in transport across the membrane; receptor molecules which selectively bind hormones, drugs and other agents, mediating their signal to the cell; and others with water-filled pores that allow exchange across the cell membrane of water, ions and small molecules, related to concentration and electrical gradients. The enclosed cytoplasm contains the intracellular fluid and a great number and variety of structures, some surrounded by their own membrane, including the nucleus containing the chromosomes that carry the genes, and mitochondria in all cells where oxidative metabolism occurs. See also membrane potential, potassium, sodium, sodium-potassium (Na-K) pump.
cytoplasm, containing a nucleus and a variety of organelles, enclosed within a membrane envelop
mast cell connective tissue cell with prominent granular cytoplasm; releases histamine; triggers hypersensitivity reactions
red blood cell erythrocyte
Schwann cell ectodermal cells forming the myelin envelop surrounding individual nerve axons within peripheral nerve tissue
sickle cell abnormal crescentic erythrocytes characteristic of sickle-cell anaemia, carrying abnormal haemoglobin (HbS) and causing decreased tissue oxygenation
stem cell universal precursor cell with the ability to transform into specific tissue cells
white blood cell leukocyte
1. In biology, the basic, structural and functional units from which living organisms and tissues are built. A cell consists of a nucleus surrounded by all the cellular contents (cytoplasm) including various organelles (mitochondria, Golgi apparatus, lysosomes, ribosomes, etc.) and inclusions (glycogen, melanin, triglycerides, etc.) suspended in intracellular fluid (water, proteins, carbohydrates, lipids, inorganic and organic substances) all enclosed in a plasma membrane. There are many types of cells (blood cells, connective tissue cells, epithelial cells, muscle cells, nerve cells, secretory cells, etc.). Living cells are capable of reproduction (for body growth, wound healing, etc.) by mitotic activity.
2. In optics, a rim in a trial frame or in an optical instrument into which a lens can be placed.
A cell See M cell.
acinar cell A type of cell found within the body of the lacrimal gland. This cell lines the lumens of glands in a lobular pattern and produces a serous secretion.
amacrine cell Retinal cell located in the inner nuclear layer connecting ganglion cells with bipolar cells. Some have an ascending axon synapsing with receptors.
binocular cell A cell in the visual cortex that responds to stimulation from both eyes. It may, however, show an ocular dominance for either eye. It responds more strongly when corresponding regions of each eye are stimulated by targets of similar size and orientation. See cortical column; hypercolumn.
bipolar cell Retinal cell located in the inner nuclear layer connecting the photoreceptors with amacrine and ganglion cells.
C cell A retinal ganglion cell with slow axonal conduction which sends information to the superior colliculus and to the centre involved in the control of pupillary diameter, rather than to the lateral geniculate body. There are very few such cells. Syn. Pγ cell; W cell (thus called in the cat).
Cajal's cell See astrocytes.
clump cell Large, pigmented round cells found in the pupillary zone of the iris stroma. They are considered to be macrophages containing mainly melanin granules. The number of these cells increases with age.
colour-opponent cell's Cells which respond by increasing response to light of some wavelengths and decreasing their response to others (usually complementary). If the light stimulus contains both sets of wavelengths the two responses tend to cancel each other. Two types of cells have been identified: red-green cells and blue-yellow cells. These cells are found mainly in the lateral geniculate bodies but also among retinal ganglion cells, and they form the blobs in the visual cortex. The responses of these cells support Hering's theory of colour vision. Syn. opponent-process cell (although this term also includes a cell that increases its response to white light and decreases its response to dark). See blobs; Hering's of colour vision theory.
complex cell A cell in the visual cortex whose receptive field consists of a large responsive area, approximately rectangular in shape, surrounded by an inhibitory region. The stimulus, which is usually a slit or a straight line, gives an optimum response if appropriately orientated but falling anywhere within the excitatory area. These cells tend to respond optimally to the movement of a specifically orientated slit. Many complex cells also respond better when the optimally orientated slit is moved in one direction rather than in the opposite direction. In general, complex cells show non-linear spatial summation properties. See visual area; hypercomplex cell; simple cell; receptive field; summation.
cone cell Photoreceptor of the retina which connects with a bipolar cell and is involved in colour vision and high visual acuity and which functions in photopic vision. The outer segment of the cell is conical in shape, except in the fovea centralis where it is rod-like. In the outer segment (i.e. the part closest to the pigment epithelium) are contained hollow discs (or lamellae), the membranes of which are joined together and are also continuous with the boundary membrane of the cone cell. The visual pigments are contained in these discs. There are three types of cones, each containing a different pigment sensitive to a different part of the light spectrum. They are referred to as long-wave-sensitive (or L-cones), medium-wave-sensitive (or M-cones) and short-wave-sensitive (or S-cones). There are about six million cones in the retina, with the greatest concentration in the macular area (Fig. C4). See cone pedicle; Stiles-Crawford effect; ellipsoid; foveola; macula; visual pigment; duplicity theory; photopic vision.
fixed cell See corneal corpuscle.
ganglion cell 1. Retinal cell that connects the bipolars and other cells in the inner plexiform layer with the lateral geniculate body. The axons of the ganglion cells constitute the optic nerve fibres. There are many types of ganglion cells. The two major types are: the magno (M or parasol) ganglion cells which project mainly to the magnocellular layers of the lateral geniculate bodies; and the parvo (P) ganglion cells which project to the parvocellular layers of the lateral geniculate bodies. Two types of P ganglion cells are noted: P1, which are midget cells and have small dendritic fields and P2, which have large dendritic fields. M and P cells comprise about 10% and 82% of the ganglion cells respectively. 2. One of a collection of nerve cell bodies found in a ganglion. See C cell; M cell; P cell; melanopsin.
glial cell's Cells found throughout the nervous system. They provide support and nutrition for neurons, as well as being involved in the operation of the brain, especially the fluid surrounding the neurons and their synapses. They are also believed to be involved in the reuptake of neurotransmitters from within the synaptic cleft. There are three types of glial cells: astrocytes; microglia; oligodendroglia. Syn. glia; neuroglia.
goblet cell Cell of the conjunctival epithelium which secretes mucin. See glands of Henle; mucin; xerophthalmia.
horizontal cell Retinal cell located in the inner nuclear layer which connects several cones and rods together.
hypercomplex cell A cell in the visual cortex that receives inputs from several simple and complex cells and therefore has an even more elaborate receptive field than a complex cell. It is most effectively stimulated by a stimulus of a specific size and of a specific orientation and which is moved in a specific direction. See complex cell; simple cell.
Langerhans' cell's Dendritic cells located mainly in the epidermis, mucous membranes and lymph nodes. They have surface receptors for immunoglobulin (Fc), complement (C3) and surface HLA-DR (Ia) antigen. Langerhans' cells are also found in the conjunctival epithelium and among the basal cells, mainly of the peripheral corneal epithelium. They have antigenic functions, stimulate T-lymphocytes, prostaglandin production and participate in cutaneous delayed hypersensitivity and corneal graft rejection. Extended wear of contact lenses tends to induce an increase of these cells. They are also found in histiocytic tumours.
M cell A retinal ganglion cell, mainly located in the periphery of the retina and which assists in movement perception. M cells tend to give transient responses to stimuli and to have non-linear spatial summation properties. This cell transmits information principally to the magno cells of the lateral geniculate bodies. Syn. A cell; Pαcell; Y cell (thus called in the cat).
magno cell See ganglion cell; lateral geniculate bodies.
midget cell See ganglion cell.
Mueller's cell Neuroglial cell in the retina with its nucleus in the inner nuclear layer and with fibres extending from the external to the internal limiting membrane. These cells support the neurons of the retina and possibly assist in their metabolism. Syn. Müller cell.
orientation-specific cell A cell that responds best to specifically orientated lines. This is the case for almost all cells in the visual cortex. Examples: complex cell; simple cell. See complex cell; simple cell; receptive field.
P cell A retinal ganglion cell, mainly located in the central region of the retina and which assists in high acuity and colour vision. P cells tend to give sustained responses to stimuli and to have linear spatial summation properties. This is the most common type of ganglion cells (about 82%). This cell transmits information principally to the parvo cells of the lateral geniculate bodies. Syn. B cell; Pβcell; X cell (thus called in the cat).
parasol cell See ganglion cell.
parvo cell See ganglion cell; lateral geniculate bodies.
rod cell Photoreceptor cell of the retina which connects with a bipolar cell. It contains rhodopsin and is involved in scotopic vision. The molecules of rhodopsin are contained in about 1000 hollow discs (double lamellae or membranes), which are isolated from each other and from the boundary membrane of the rod cell. These discs are found in the outer segment (i.e. the part closest to the pigment epithelium) of the cell. There are about 100 million rod cells throughout the retina; only a small area, the foveola, is free of rods (Fig. C4). See eccentricity; ellipsoid; foveola; rhodopsin; rod spherule; duplicity theory; scotopic vision.
Schwann cell A cell whose membrane spirals around the axon with layers of myelin in between each coil, as well as being a source of the myelin sheath. The cell provides insulation to the axon. It covers about one millimetre, so that hundreds may be needed to completely cover an axon. It also allows for an increase in the speed of the nervous impulse without an increase in axonal diameter. The gaps between the segments covered by the cells are called nodes of Ranvier. See action potential.
simple cell A cell in the visual cortex whose receptive field consists of an excitatory and an inhibitory area separated by a straight line, or by a long narrow strip of one response flanked on both sides by larger regions of the opposite response. Responses occur only to a straight line or a narrow strip orientated approximately parallel to the boundary/ies between the two areas. In general, simple cells show linear spatial summation properties. They are presumably the first cells where the nervous impulses are processed as they enter the visual cortex. See visual area; complex cell; receptive field.
squamous cell See corneal epithelium.
W cell See C cell.
wing cell See corneal epithelium.
X cell See P cell.
Y cell See M cell.
Fig. C4 Structures of a rod and a cone cell of the retina (ELM, external limiting membrane; ONL, outer nuclear layer; OPL, outer plexiform layer)
Table C1 distinguishing features of the two principal types of ganglion cells of the retina
properties P cell (X cell) M cell (Y cell)
size of cell body small large
dendritic spread small medium/large
receptive field size small medium/large
retinal distribution 90% of these at the macula 5% of these at the macula; about 13% overall
projection LGN parvocellular layers LGN magnocellular layers
type of response sustained transient
light sensitivity low high
wavelength response selective (except P cells) non-selective
spatial sensitivity fine target detail large target detail
temporal sensitivity low target velocity high target velocity
1. Smallest unit of living structure capable of independent existence, composed of a membrane-enclosed mass of protoplasm and containing a nucleus or nucleoid; highly variable and specialized in both structure and function, although all must at some stage replicate proteins and nucleic acids, use energy, and reproduce themselves.
2. Small closed or partly closed cavity; compartment or hollow receptacle.
cell(s),
n the basic unit of vital tissue. One of a large variety of microscopic protoplasmic masses that make up organized tissues. Each cell has a cell membrane, protoplasm, nucleus, and a variety of inclusion bodies. Each type of cell is a living unit with its own metabolic requirements, functions, permeability, ability to differentiate into other cells, reproducibility, and life expectancy.
cell, beta,
n any cell that produces insulin in the islets of Langerhans region of the pancreas.
cell, bone-forming,
n.pl See osteoblast.
cell, central, of the dental papillae,
n the inner cells of the dental papilla within the concavity of the enamel organ that are the primordium of the pulp.
1. the basic structural unit of living organisms.
2. a small more or less enclosed space.
All living cells arise from other cells, either by division of one cell to make two, as in mitosis and meiosis, or by fusion of two cells to make one, as in the union of the sperm and ovum to make the zygote in sexual reproduction.
All cells are bounded by a structure called the cell membrane or plasma membrane, which is a lipid bilayer composed of two layers of phospholipids. Each layer is one molecule thick with the charged, hydrophilic end of the lipid molecules on the surface of the membrane and the uncharged hydrophobic fatty acid tails in the interior of the membrane.
Cells are divided into two classes, eukaryotic cells and prokaryotic cells:
Eukaryotic cells have a true nucleus, which contains the genetic material, composed of the chromosomes, each of which is a long linear deoxyribonucleic acid (DNA) molecule associated with protein. The nucleus is bounded by a nuclear membrane, which is composed of two lipid bilayer membranes.
Prokaryotic cells, the bacteria, have no nucleus, and their genetic material, consisting of a single circular naked DNA molecule, is not separated from the rest of the cell by a nuclear membrane.
Eukaryotic cells are larger and more complex than prokaryotic cells. They also have membrane-bounded structures, such as mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum and lysosomes, that prokaryotic cells lack.
The contents of a cell are referred to collectively as the protoplasm. In eukaryotic cells the contents of the nucleus are referred to as nucleoplasm and the rest of the protoplasm as the cytoplasm.
The lipid bilayer of eukaryotic cells is impermeable to many substances, such as ions, sugars and amino acids; however, membrane proteins selectively move specific substances through the cell membrane by active or passive transport. Water, gases such as oxygen and carbon dioxide, and nonpolar compounds pass through the cell membrane by diffusion. Materials can also be engulfed and taken into the cell enclosed in a portion of the cell membrane. This is called phagocytosis when solids are ingested and pinocytosis when liquids are ingested. The reverse process is called exocytosis. All of these processes permit the cell to maintain an internal environment different from its exterior. See also body fluids.
The cells of the body differentiate during development into many specialized types with specific tasks to perform. Cells are organized into tissues and tissues into organs. Embedded in the cell membrane are a wide range of molecules that vary with the cell type and are typically composed of proteins or glycoproteins that have a cytoplasmic transmembrane and external domains. These molecules serve as cell receptors and are involved in signal transduction for a wide range of ligands, including hormones, cytokines and incidentally serve as receptors for viruses and drugs.
See also betz cells, gaucher's cells, golgi's cells, hela cells, hürthle cell, kupffer's cells, merkel cell, mesangial cell, neuroendocrine cell.
accessory c's
macrophages involved in the processing and presentation of antigens making them immunogenic.
acinar cell, acinous cell
any of the cells lining an acinus, especially applied to the zymogen-secreting cells of the pancreatic acini.
adherent cell
one that adheres to the glass or plastic container in cell cultures, to form the monolayer. See also cell culture.
alpha c's
1. cells in the islets of Langerhans that secrete glucagon.
2. acidophilic cells of the anterior pituitary.
APUD c's
see apud cells.
argentaffin c's
enterochromaffin cells containing cytoplasmic granules capable of reducing silver compounds, located throughout the gastrointestinal tract, chiefly in the basilar portions of the gastric glands and the crypts of Lieberkühn. They secrete serotonin.
an immature neutrophil in which the nucleus is not lobulated but is in the form of a continuous band, horseshoe shaped, twisted or coiled. Called also band-form granulocyte and stab cell.
an early keratinocyte, present in the basal layer of the epidermis.
basket c's
cells in the cerebellar cortex whose axons carry basket-like groups of fibrils which enclose the cell body of each Purkinje cell.
beta c's
1. basophilic cells in the pancreas that secrete insulin and make up most of the bulk of the islets of Langerhans; they contain granules that are soluble in alcohol.
2. basophilic cells of the anterior pituitary.
one of the formed elements of the blood. See also blood.
cell body
the nucleus of the cell and the adjacent cytoplasm in cells which have processes, e g. neurons which consist of a cell body, an axon and dendrites.
a nucleated cell in the lacunae of bone. Called also osteocyte.
chromaffin c's
cells whose cytoplasm shows fine brown granules when stained with potassium bichromate, occurring in the adrenal medulla and in scattered groups in various organs and throughout the body.
any of the cells derived from the fertilized ovum by mitosis; a blastomere.
cell count
see erythrocyte, leukocyte, milk cell counts.
see cell culture.
see cell cycle.
a cell formed by division of a mother cell.
cell dehydration
fluid loss from cells due to elevation of the osmotic pressure of blood and tissue fluid; a potent stimulus to thirst.
macrophage-like cells with long, filamentous processes located in the cortex of lymph nodes and the skin. Important in antigen trapping, processing and presentation. See also langerhans' cell.
the process whereby cells become specialized usually with concurrent loss of reproductive capacity.
a stem cell of fetal origin. See stem cell (below).
epithelioid cell
enlarged macrophages with enlarged lysosomes and much endoplasmic reticulum. May fuse to form multinucleated giant cell (below).
epsilon cell
one of the groups of acidophilic cells in the adenohypophysis. Contains granules that stain with azocarmine dye.
a cell with a vacuolated appearance due to the presence of complex lipoids; seen in xanthoma.
cell fusion
see syncytial giant cell.
a large nerve cell, especially one of those of the spinal ganglia.
see germ cell.
a very large, multinucleate cell; applied to megakaryocytes of bone marrow, to giant cells formed by coalescence and fusion of macrophages occurring in infectious granulomas and about foreign bodies, and to certain cancer cells.
glial c's
neuroglial cells.
a unicellular mucous gland found in the epithelium of various mucous membranes, especially that of the respiratory passages and intestines.
granular cell
one containing granules, such as a keratinocyte in the stratum granulosum of the epidermis, when it contains a dense collection of darkly staining granules.
see taste bud.
heart failure c's, heart lesion c's
iron-containing, rust-colored macrophages found in the pulmonary alveoli in congestive heart failure.
schistocyte.
a subset of T lymphocytes which cooperate with B and other T lymphocytes for the synthesis of antibodies to many antigens; they play an integral role in immunoregulation.
hybrid cell
a mononucleate cell produced from a binucleate heterokaryon after the latter undergoes mitosis. Such cells are initially unstable, tending to lose randomly some of the double complement of chromosomes. Used for mapping genes to particular chromosomes. See also heterokaryon, hybridoma.
immunologically competent cell
see immunocyte.
interstitial c's
the cells of the connective tissue of the ovary or of the testis (Leydig's cells) which furnish the internal secretion of those structures, i.e. testosterone.
islet c's
cells composing the islets of Langerhans in the pancreas. See alpha cells, beta cells (above).
juxtaglomerular c's
specialized cells, containing secretory granules, located in the tunica media of the afferent glomerular arterioles. They cause aldosterone production by secreting the enzyme renin and play a role in the regulation of blood pressure and fluid balance.
K c's, killer c's
T lymphocytes or null lymphocytes that have cytotoxic activity against target cells coated with specific IgG antibody.
lacis cell
accumulation of cells between the arterioles at the glomerular hilus. Called also granular cell.
lacunar cell
precursor of the malignant interdigitating reticular cell in Hodgkin-like lymphoma in humans.
LE cell
a mature neutrophilic polymorphonuclear leukocyte characteristic of lupus erythematosus. See also lupus erythematosus (le) cell.
Leydig's c's
interstitial cells of the testis, which secrete testosterone.
lutein c's
the plump, pale-staining, polyhedral cells of the corpus luteum.
lymph cell
lymphocyte.
lymphoid c's
lymphocytes and plasma cells.
a connective tissue cell that has basophilic, metachromatic cytoplasmic granules that contain histamine, heparin, hyaluronic acid, slow-reacting substance of anaphylaxis (SRS-A), and, in some species, serotonin. Have Fc receptors specific for IgE in the cell membrane.
cell-mediated immune reaction
see cellular immunity.
cell migration
movement of cells from their place of origin to other tissues; one of the fundamental processes of development.
see microglia. See also neuroglia cells (below).
milk cell count
see milk cell counts.
a cell that divides to form new, or daughter, cells.
Mott cell
a plasma cell with large, clear cytoplasmic pockets.
natural killer c's, NK c's
cells capable of mediating cytotoxic reactions without themselves being specifically sensitized against the target.
any cell of the nervous system; a neuron.
cell nests
see isogenous groups.
neuroglia c's, neuroglial c's
see neuroglia.
null c's
lymphocyte-like cells that lack specific antigen receptors and other surface markers characteristic of B and T lymphocytes; they include K and NK cells; their numbers are elevated in active systemic lupus erythematosus and other disease states.
olfactory c's
a set of specialized cells of the mucous membrane of the nose; the receptors for smell.
parafollicular c's
see c cell.
Pick's c's
round, oval or polyhedral cells with foamy, lipid-containing cytoplasm found in the bone marrow and spleen in Niemann-Pick disease.
a spherical or ellipsoidal cell with a single, eccentrically placed nucleus containing dense masses of chromatin in a wheel-spoke arrangement, an area of perinuclear clearing which contains the Golgi apparatus, and generally abundant cytoplasm. Plasma cells are produced by cell division of B lymphocytes following antigen stimulation and are involved in the synthesis and release of antibody. Called also plasmacyte and plasmocyte.
a dividing keratinocyte of the prickle-cell layer of the epidermis, with delicate radiating process connecting with other similar cells.
see prokaryote.
Purkinje's c's
large branching cells of the middle layer of the cerebellar cortex.
red cell, red blood cell
erythrocyte.
Reed-Sternberg c's
giant histiocytic cells, typically multinucleate, which are the common histological characteristic of Hodgkin's disease in humans.
reticular c's
the cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow and spleen. They are weakly phagocytic, stromal in origin and are distinct from the monocyte-macrophage system.
a cell of the reticuloendothelial system.
any of the large nucleated cells whose cell membrane spirally enwraps the axons of myelinated peripheral neurons supplying the myelin sheath between two nodes of Ranvier.
Sertoli c's
elongated cells in the tubules of the testes to which the spermatids become attached; they provide support, protection and, apparently, nutrition until the spermatids are transformed into mature spermatozoa.
a crescentic or sickle-shaped erythrocyte seen in some humans and deer. The abnormal shape caused by the presence of varying proportions of hemoglobin S.
a cell in which the nucleus has been pressed to one side by an accumulation of intracytoplasmic mucin.
somatic c's
the cells of the body other than the germ cells.
see fluorescence-activated cell sorter.
cell specialization
conversion of a simple cell type into a specialized cell type capable of a special function, e.g. a secretory cell; a major part of the growth of an embryo and the differentiation of basic mesenchymal tissue into specialized organs.
spindle cell
spindle shaped cells of the dermis or subcutis; principal component of spindle cell tumors.
spur cell
spiculed mature erythrocyte.
squamous c's
flat, scalelike epithelial cells.
stab cell
see band cell (above).
any star-shaped cell, as a Kupffer cell or astrocyte, having many filaments extending in all directions.
1. any precursor cell.
2. a primitive hematopoietic cell that is capable of self-replicating or differentiating into precursor cells of erythrocytes or any of the leukocytes.
an erythrocyte containing granules that take a basic or bluish stain with Wright's stain.
suppressor c's
a not well defined subset of T lymphocytes that are reported to inhibit antibody and cell-mediated immune responses. They may play a role in immunoregulation, and are believed to be abnormal in various autoimmune and other immunological disease states. See also T lymphocytes.
1. an abnormally thin erythrocyte showing, when stained, a dark center and a peripheral ring of hemoglobin, separated by a pale, unstained zone containing less hemoglobin; seen in various anemias and other disorders. Called also codocyte.
3. cell containing nonself antigens in its cell membranes that is a target for nonimmune and immune cytolysis, e.g. virus-infected or tumor cell.
taste c's
cells in the taste buds associated with the nerves of taste.
see glandular therapy.
totipotential cell
an embryonic cell that is capable of developing into any type of body cell.
Türk's cell
a lymphocyte with increased basophilia.
visual c's
the neuroepithelial elements of the retina.
white cell, white blood cell
little finger
little league elbow
Little League shoulder
Little Leaguer's elbow
Little lion dog
Little Person
little toe
little toe V
Little White
Little Women Syndrome
Little Yellow Pill
Little, Sir Ernest Gordon Graham
Little, William J.
Little’s Disease
little-leaf horsebrush
Little's disease
Litton, Clyde
littoral cells
littoral zone
Littre
Littré gland
Littre hernia
Littre, Alexis
Littré’s glands
Littre's hernia
littritis
Litzmann
Litzmann obliquity
Litzmann, Karl K.T.
live attenuated influenza vaccine
live attenuated measles virus vaccine
live attenuated vaccine
live attenuated vaccines
live born pigs
live cell analysis
live food
live measles and mumps virus vaccine
live measles and rubella virus vaccine
live measles virus vaccine
live measles, mumps, and rubella virus vaccine
Littlewoods Shop Direct Group
littlie
littling
littlish
Littoisten Työväen Urheilijat
Litton Amecon Space System Operations
Litton formula
Litton Naval Tactical Data System
Litton Network Access Systems
Litton Precision Products International, Inc.
Littoral (military)
Littoral Airborne Sensor Hyperspectral
Littoral and Mine Warfare
Littoral and Riverine Survey Squadron
Littoral Area Air Defense
Littoral Battlespace Joint Service
Littoral Cell Angioma
Littoral Combat
littoral current
Littoral Deposits
Littoral drift
Littoral Ecosystem Risk Assessment Model
Littoral Fauna
Littoral Flora
littoral land
Littoral Penetration Area
Littoral Penetration Point
Littoral Region
Littoral Remote Sensing
Littoral Rights
Littoral Sea Mine
littoral sediments
Littoral Shoal
Littoral Surveillance Radar System
Littoral Surveillance System
littoral transport
Littoral Warfare Advanced Development
Littoral Warfare Data
Littoral Warfare Training Center
Littoral Warfare Training Complex