Hematopoietic analyses. (A) Gross appearance of E12.5 fetuses. Arrows indicate hemorrhages. (B) Expression from the Runx1lz allele in E11.5 Runx1f/lz and Runx1f/lz Tg(Tek-cre) littermates. The individual Runx1+ cells distributed throughout the Runx1f/lz fetus are absent in the Runx1f/lz Tg(Tek-cre) fetus (regions in head indicated by black arrows are enlarged in panels to the right). White arrows indicate fetal livers. (C) Transverse section through the AGM region and fetal liver of E10.5 fetuses illustrating the lack of Runx1+ progenitors in the center of the fetal liver (fl) in Runx1f/lz Tg(Tek-cre) animals. (D) C-kit+ hematopoietic clusters (hc's) in the umbilical artery, whole mount. (E) Colony-forming assays represented as total colonies per organ. Error bars represent 95% confidence intervals. Yolk sac (E9.5): nexperiments = 3, nf/+ = 6, nf/rd = 6, nf/+;Tek-cre = 5, nf/rd; Tek-cre = 5. Fetal liver (E11.5): nexperiments = 3, nf/+ = 5, nf/rd = 11, nf/+;Tek-cre = 3, nf/rd; Tek-cre = 8. Dorsal aorta and mesenchyme (E11.5): nexperiments = 4, nf/+ = 6, nf/rd = 11, nf/+;Tek-cre = 11, nf/rd;Tek-cre = 8. The difference between Runx1f/+ and all other genotypes is significant at P < .001. (F) FACS analysis of the yolk sac (E9.5), fetal liver (E11.5), and AGM region plus vitelline and umbilical (V + U) arteries (E11.5). The average percentage ± SD of c-kit+CD41+ cells in the yolk sac is 5.8 ± 1.1 Runx1f/+; 0.5 ± 0.5 Runx1f/lz Tg(Tek-cre), and of CD45+CD41+ cells is 4.4 ± 0.6 Runx1f/+; 0.5 ± 0.3 Runx1f/lz Tg(Tek-cre). The average percentage of c-kit+CD41+ cells in the fetal liver is 5.0 ± 0.8 Runx1f/+; 0.4 ± 0.4 Runx1f/lz Tg(Tek-cre), and CD45+CD41+ cells is 6.3 ± 2.0 Runx1f/+; 1.4 ± 1.4 Runx1f/lz Tg(Tek-cre). Average c-kit+CD41+ cells in the AGM, V + U is 1.1 ± 0.7 Runx1f/+; 0.0 ± 0.0 Runx1f/lz Tg(Tek-cre), and of CD45+CD41+ cells is 1.2 ± 1.0 Runx1f/+; 0.1 ± 0.1 Runx1f/lz Tg(Tek-cre). (G) Assessment of excision efficiency by Tek-cre, determined by comparing the percentage of β-gal+ fetal liver cells in ROSA26 and R26R Tg(Tek-cre) mice. Representative plots and histograms are shown. Histograms indicate the percentage of β-gal+ and β-gal- cells expressing (or not expressing, in the case of Ter119) the indicated cell-surface markers.
