The<unk> , in humans, is oval in shape and is a pea-sized<unk>  that sits in a protective bony enclosure called the sella turcica. It is composed of two lobes: anterior and posterior, with the intermediate lobe that joins the two regions. In many animals, these three lobes are distinct. The intermediate is avascular and almost absent in human beings. The intermediate lobe is present in many animal species, in particular in rodents, mice and rats, that have been used extensively to study<unk>  development and function. In all animals, the fleshy,<unk> ular anterior<unk>  is distinct from the neural composition of the posterior<unk> , which is an extension of the hypothalamus. Histology of<unk>  The height of the<unk>  ranges from 5.3 to 7.0 mm. The volume o<unk>  ranges from 200 to 440 mm3. Anterior The anterior<unk>  arises from an invagination of the oral ectoderm (Rathke's pouch). This contrasts with the posterior<unk> , which originates from neuroectoderm. Endocrine cells of the anterior<unk>  are controlled by regulatory hormones released by parvocellular neurosecretory cells in the hypothalamic capillaries leading to infundibular blood vessels, which in turn lead to a second capillary bed in the anterior<unk> . This vascular relationship constitutes the hypothalamo-hypophyseal portal system. Diffusing out of the second capillary bed, the hypothalamic releasing hormones then bind to anterior<unk>  endocrine cells, upregulating or downregulating their release of hormones. The anterior lobe of the<unk>  can be divided into the pars tuberalis (pars<unk> ularis) and pars distalis (pars<unk> ularis) that constitutes ~80% of the<unk> . The pars intermedia (the intermediate lobe) lies between the pars distalis and the pars tuberalis, and is rudimentary in the human, although in other species it is more developed. It develops from a depression in the dorsal wall of the pharynx (stomal part) known as Rathke's pouch. The anterior<unk>  contains several different types of cells that synthesize and secrete hormones. Usually there is one type of cell for each major hormone formed in anterior<unk> . With special stains attached to high-affinity antibodies that bind with distinctive hormone, at least 5 types of cells can be differentiated. S.No. Type of cell Hormone secreted Percentage of type of cell 1. Somatotropes human growth hormone (hGH) 30-50% 2. Corticotropes adrenocorticotropin (ACTH) 20% 3. Thyrotropes thyroid stimulating hormone (TSH) 3–5% 4. Gonadotropes gonadotropic hormone i.e., both luteinizing hormone (LH) and follicle stimulating hormone (FSH) 3–5% 5. Lactotropes prolactin (PRL) 3–5% Posterior The posterior lobe develops as an extension of the hypothalamus, from the floor of the third ventricle. The posterior<unk>  hormones are synthesized by cell bodies in the hypothalamus. The magnocellular neurosecretory cells, of the supraoptic and paraventricular nuclei located in the hypothalamus, project axons down the infundibulum to terminals in the posterior<unk> . This simple arrangement differs sharply from that of the adjacent anterior<unk> , which does not develop from the hypothalamus. The release of<unk>  hormones by both the anterior and posterior lobes is under the control of the hypothalamus, albeit in different ways.
Pituitary gland
Adrenal gland
Adrenal cortex
Allothalamus
Kidney
Lens
Lens 
Liver