Figure 3.

Control and Gfi-1b mutant embryos and peripheral blood at different gestational ages. Control (a,e,i) and mutant (c,g,k) embryos at E10.5, E12.5, and E14.5 and May–Grunwald–Giemsa stains of their corresponding yolk sac blood (b, f, and j, and d, h, and l, respectively). Gfi-1b^−/− embryos show aberrant primitive erythropoiesis characterized by abnormal cell morphology (d) and delayed cellular maturation (h,l). Embryos die by E15 (k) from a failure of fetal liver erythropoiesis, resulting in the complete absence of definitive enucleated erythrocytes (l).