Histology of spleen and liver from fit1 mutant mice. (A and B) Photomicrographs of hematoxylin and eosin-stained sections of (A) wild-type littermate (c^ch +/c^ch +) and (B) fit1^4397SB spleen. Erythroid precursors (darker staining cells) appear to be present in larger numbers in the fit1 mutant spleen, and in the mutant spleen, the white pulp areas appear smaller and less well defined. (C and D) Photomicrographs of Prussian blue stained sections from wild-type littermate liver (C) and fit1^4397SB mutant liver (D). Increased iron stores can be seen in the fit1 mutant liver as dark staining within several cells.