Foxc2−/− mouse embryos show defective definitive hematopoiesis. (A) Representative AGM sections of E10.5 Foxc2−/− mouse embryos and wild-type littermates with anti-Runx1 antibody staining are shown (left panel). The dorsal aorta region is shown. Quantification of Runx1-positive cells are shown on the right (3 sections per embryo; Foxc2+/+, n = 4; Foxc2−/−, n = 5; Volocity version 5.1.0, Improvision Ltd.). (B) Peripheral blood smears of a representative E13.5 Foxc2−/− embryo and a wild-type littermate are shown on the left, and the percentages of primitive, nucleated erythroblast and definitive, enucleated erythrocytes are shown on the right. (C) Real time RT-PCR of peripheral blood is shown. Gene expressions relative to wild-type controls are plotted. *P < .05 by Student t test in comparison with Foxc2+/+.