Encyclopedia of Cancer (2016)
Cells without nuclei which circulate in the blood. They are involved in thrombus (blood clot) formation. They contain fibrinogen, factor V, vitronectin, thrombospondin, and von Willebrand factor, which are released upon platelet activation. Platelets are produced in the bone marrow. The progenitor cell for platelets is the megakaryocyte which sheds platelets into the circulation.