Tartrate resistant acid phosphatase positive<unk>  in cell culture Illustrated cross-section of an activated<unk>  An<unk>  is a large multinucleated cell and human<unk> s on bone typically have five nuclei and are 150–200 µm in diameter. When<unk> -inducing cytokines are used to convert macrophages to<unk> s, very large cells that may reach 100 µm in diameter<unk> cur. These may have dozens of nuclei, and typically express major<unk>  proteins but have significant differences from cells in living bone because of the not-natural substrate. The size of the multinucleated assembled<unk>  allows it to focus the ion transport, protein secretory and vesicular transport capabilities of many macrophages on a localized area of bone. Location In bone,<unk> s are found in pits in the bone surface which are called resorption bays, or Howship's lacunae.<unk> s are characterized by a cytoplasm with a homogeneous, "foamy" appearance. This appearance is due to a high concentration of vesicles and vacuoles. These vacuoles include lysosomes filled with acid phosphatase. This permits characterization of<unk> s by their staining for high expression of tartrate resistant acid phosphatase (TRAP) and cathepsin K.<unk>  rough endoplasmic reticulum is sparse, and the Golgi complex is extensive. At a site of active bone resorption, the<unk>  forms a specialized cell membrane, the "ruffled border", that opposes the surface of the bone tissue. This extensively folded or ruffled border facilitates bone removal by dramatically increasing the cell surface for secretion and uptake of the resorption compartment contents and is a morphologic characteristic of an<unk>  that is actively resorbing bone.
Osteoclast
Lymphoblast
Prolymphocyte
Plasma cell
Dendritic cell
Podocyte
Progenitor cell
Monocyte