Fig. 2. Temporal kinetics of endothelial and hematopoietic progenitors in early gastrulating embryos. The numbers of endothelial and stroma-dependent hematopoietic progenitors, and CFU-c per embryo were measured in precisely staged embryos from E5.5 to E7.75. Five to 14 embryos were examined for endothelial and hematopoietic progenitors at each time point. Seven to 11 embryos were examined for CFU-c at each time point. Data are expressed in mean±s.d. per embryo. Sigmoid dose-response curves were used for approximation.