Increased and aberrant megakaryopoiesis in boo/boo mice. FACS for CD41 and the DNA intercalating dye DRAQ5 in bone marrow and spleen of boo/boo and wild-type (+/+) littermates. There is a marked increase in large CD41⁺ cells (megakarocytes) in spleen (∼ 20-fold) and bone marrow (∼ 8-fold). Ploidy analysis shows a “right shift” in boo/boo spleen (ie, more megakaryocytes have > 8n ploidy and less have 2n ploidy).