Define Platelets
Blood platelets, the third blood cells are the smallest formed by the pinching of a very large bone marrow cell called megakaryocyte. Platelets literally mean a small plate. The platelets form a plug to stop bleeding when an injury disrupts the lining of the blood vessel. Their diameter is about 2-3 μm, hence they are much smaller than erythrocytes. Their density in the blood is 2, 00,000-3, 00,000 /mm3.