Platelet (Thrombocyte)

A **platelet** is not a cell but rather a fragment of the cytoplasm of a cell called amegakaryocyte that is surrounded by a plasma membrane.. Platelets are relatively small, 2–4 µm in diameter, but numerous, with typically 150,000‒160,000 per µL of blood. After entering the circulation, approximately one-third migrate to the spleen for storage for later release in response to any rupture in a blood vessel. They then become activated to perform their primary function, which is to limit blood loss. Platelets remain only about 10 days, then are phagocytized by macrophages. Platelets are critical to hemostasis, the stoppage of blood flow following damage to a vessel. They also secrete a variety of growth factors essential for growth and repair of tissue, particularly connective tissue. Infusions of concentrated platelets are now being used in some therapies to stimulate healing.



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## Keywords
platelet