Platelets or thrombocytes are the cell fragments circulating in the blood that are involved in the cellular mechanisms of primary hemostasis leading to the formation of blood clots.
Dysfunction or low levels of platelets predisposes to bleeding, while high levels, although usually asymptomatic, may increase the risk of thrombosis.
Platelets are produced in the bone marrow; the progenitor cell for platelets is the megakaryocyte. It is about twelve times larger than an erythrocyte, possesses a lobed nucleus and sheds platelets into the circulation.
Alternative protein names include: CD62P; GMP140; GMRP; Granule membrane protein 140; Granulocyte membrane protein; GRMP; LECAM 3; LECAM3; Leukocyte endothelial cell adhesion molecule 3; PADGEM; Platelet activation dependent granule external membrane protein; PSEL; SELP