Peripheral blood smears from control, Stat5a/b^{f/f; TC}, and Stat5a/b^−/− E14.5 embryos and neonates, subjected to Giemsa staining. Peripheral blood smears revealed microcytosis, anisocytosis, and hypochromia in Stat5a/b mutant mice, suggestive of iron deficiency. An increase in nucleated erythroblasts (long →) and reticulocytes (short →) further indicates stressed erythropoiesis in mutant mice. indicates mature red blood cells. Original magnifications: top and middle panels, ×200; bottom panel, ×600.