Phenotypic analysis of embryos at E11.5. (A,B) Gross appearance of surviving TGRac1^Flox/null embryos and littermate controls at E11.5. The limbs from the right side of the embryos were removed for clarity of presentation. The appearance of the littermate controls was similar for NTGRac1^Flox/Wt, NTGRac1^Flox/null, and TGRac1^Flox/Wt (hereafter referred to as “control”). The anatomic region of the fetal liver is delineated and noted by arrows. The arrowheads point to accumulation of blood in cephalic regions as well as areas underlying the spinal cord, a phenotype previously noted in mutant animals deficient in hematopoietic cell production at the fetal liver stage. (C) Quantitative analysis of fetal liver hematopoiesis as analyzed by CFU/FL of F2 embryos at E11.5. Data represent mean (± SD) of at least 3 embryos analyzed for each genotype. *P < .01, TGRac1^Flox/null versus all other genotypes.