Impaired megakaryocytic colony formation from Cre;Scl^fl/fl MkPs. Bone marrow progenitors (CMP [A], MEP [B], MkP [C]) purified from Cre;Scl^wt/wt wild-type (black bars), Cre;Scl^wt/fl heterozygous (open bars), and Cre;Scl^fl/fl homozygous (gray bars) mice were plated in methylcellulose. Colony-forming units-erythroid (CFUE), burst-forming units-erythroid (BFUE), MK, mixed, and myeloid colonies were scored at day 7. Data are the mean ± SD of 2 independent experiments performed in triplicate. *P < .01. (Bottom) Representative MK colonies grown from Cre;Scl^wt/wt and Cre;Scl^fl/fl MkPs. The photographs were taken using an inverted IX51 Olympus microscope with a Jenoptik C14 camera. Openlab, Version 3 software (Improvision) was used for image acquisition, and images were exported into Adobe Photoshop, Version CS2 (Adobe Systems). Scale bars represent 20 μm. Note the difference in the morphology and size of the colonies. A control MK shading platelet (arrow) is shown. Scale bar represents 50 μm.