Platelet Physiology and Abnormalities of Platelet Function

Abstract

THE blood platelets, approximately 2 μm in diameter and numbering 200,000 to 400,000 per cubic millimeter, are produced in the megakaryocytes of the bone marrow by the coalescence of cytoplasmic membranes formed by invaginations of the megakaryocyte surface.1 Under normal circumstances, platelets circulate in the blood for 10 days as smooth, disk-shaped cells that are nonadherent to each other and to normal vascular endothelium. Their unique biologic properties are the changes that occur when the endothelium is broken or when disruption of the vessel allows the blood to come into contact with elements of the vessel . . .