Histological examination of the liver, spleen, and peripheral blood from heterozygous mutant female mice. Proerythroblasts and megakaryocytes accumulate in the sinus of the liver inGATA-1.05 mutant females (arrow in A). (B) is a higher magnification of (A) that contains the region pointed to by the arrow. Original magnifications × 10 (A) and × 80 (B). Mitotic figures were frequently seen in accumulated proerythroblasts in the spleen (arrows in C; original magnification × 200). Proerythroblasts were also observed in the peripheral blood of heterozygous mutant female mice with severe anemia and marked splenomegaly (D; original magnification × 200). The sections (A) through (C) were stained with hematoxylin and eosin reagent, whereas the blood smear was stained with Wright-Giemsa reagent (D).