Apoptosis, proliferation, adhesion, and migration of definitive hematopoietic progenitors at E10.5. (A) Level of apoptosis of CD41⁺ definitive hematopoietic progenitors from different embryonic tissues at E10.5 analyzed by annexinV/7AAD staining and flow cytometry. Figure shows one representative experiment of 3 with similar results. Data represent means (± SD) of at least 3 embryos analyzed for each genotype. Differences between genotypes were not significant. (B) BrdU incorporation of definitive hematopoietic progenitors isolated from the yolk sac or the embryo proper of F2 embryos at E10.5. Figure shows one representative experiment of 3 with similar results. Data represent means (± SD) of at least 3 embryos analyzed for each genotype. Differences among genotypes were not significant. (C) SCF/SDF1-α induced directed migration on FN CH296-coated transwell filters of circulating E10.5 definitive hematopoietic progenitors. Data represent means (± SD) of 3 independent experiments. (D) β₁-integrin–mediated adhesion to FN CH296 of circulating E10.5 definitive hematopoietic progenitors assayed by CFU. Data represent means (± SD) of 3 independent experiments. There was no significant difference among groups. *P < .05, TGRac1^Flox/null versus control (N = 3). (■ indicates littermate control; □, TGRac1^Flox/null).