Figure 5. Prenatal lethality in mice lacking erythroid Hscb.

(A) Erythroid-specific deletion of Hscb with Epor-Cre results in death due to anemia in embryos before E14.5. Before E11.5, when the Epor-Cre becomes active, mutant embryos are somewhat hemoglobinized, whereas later embryos show extreme pallor. (B) Iron-stained histologic sections of E11.5 Hscb^fl/– Epor-Cre⁺ animals demonstrate nucleated primitive RBCs containing coarse iron-positive granules, consistent with ring sideroblasts. Original magnification, ×400; inset, original magnification, ×2000.