Platelet And Blood Group

Platelets are cytoplasmic fragments of extraordinarily large cells called megakaryocytes. Their granules contain lots of chemicals that act in the clotting process, (including serotonin, Ca2+, a variety of enzymes, ADP, and platelet derived growth factor (PDGF)). Platelets play an important role in hemostasis. Blood type is based on the presence of 2 major antigens in RBC membranes-- A and B.