What r megakaryocytes????

The megakaryocyte is a largest blood cell originating in the bone marrow. It is at least ten times larger than a normal red blood cell.  It is filled with cytoplasm that breaks up into tiny fragments to form platelets. Platelets found at sites of injury are involved in blood clotting and blood vessel repair. It has an irregular shaped nucleus that contains more DNA than the nuclei of normal cells.