Morphologic aspects of CB and PB megakaryocytic colonies.

CD34⁺ cells purified from CB or PB were assessed for their capacity to give rise to MK colonies when cultured in 0.9% methylcellulose using the same serum-free medium of the liquid suspension culture containing 50 ng/mL TPO. (A) CB-derived multifocal BFU-MK colony after 16 days of culture, showing > 100 small cells. (B) PB-derived CFU-MK colony at day 12 of culture, with few large cells. Colonies were evaluated by inverted light microscopy. (Original magnification, × 32.)