Morphology of RBCs from fit1 mutant mice. Peripheral blood smear from a c^ch +/c^ch + wild-type littermate (A) and from a cfit1^4397SB/c^26DVT mutant (B). RBCs from fit1 mutants were typically hypochromic and varied greatly in size. Scanning electron micrographs of wild-type (c^ch +/c^ch +) blood (C) and mutant (c fit1^4397SB/c fit1^4397SB ) blood (D) more clearly show the size and shape variations of the fit1 mutant RBCs. The SEM bar represents 10 mm.