Abnormal polyploidy formation in thrombocytopenic individuals.

(A) Megakaryocytes from 1 unaffected family member (IV-8) and 2 thrombocytopenic individuals (IV-10 and V-14) were tested for the ability to become polyploid after 10 to 11 days in culture. The cells with highest CD41a expression were selected and plotted as cell number (y-axis; linear scale) versus propidium iodide content (x-axis; logarithmic scale). (B) Photomicrographs demonstrate representative megakaryocytes derived by liquid culture in 10-ng/mL TPO for 7 days (magnification, 1500 ×). At left is a single megakaryocyte from an unaffected individual (IV-8); right, 2 immature megakaryocytes with cytoplasmic blebs around the periphery (IV-10).