Figure 3.

In vitro megakaryocyte differentiation from E10.5 yolk sac. (A) Phase-contrast appearance and AChE stains of representative megakaryocyte colonies at day 7 of culture. Arrows indicate proplatelet processes. AchE-positive cells stain orange [original magnification, ×320 (phase-contrast); ×1,000 (AchE)]. (B) Quantitation of megakaryocyte colony formation. Colonies were counted on day 7 of culture and expressed as the mean number of megakaryocyte colonies (MK) per 1 × 10⁵ cells plated. Error bars represent the SEM. n = number of embryos analyzed. (C) RT-PCR analysis of the murine megakaryocytic markers AChE, von Willebrand factor (vWF), GPIbα and P-selectin, from yolk sac cells cultured for 7 days in liquid culture in the presence of recombinant Tpo. Hypoxanthine ribosyltransferase (HPRT) represents “housekeeping” control gene for normalization of cDNA content. Fold decrease of mRNA levels relative to wild type (WT) (after normalization to HPRT signal) is indicated below each panel. “−RT” indicates no reverse transcriptase was added to sample.