Ccbe1^lacZ/lacZ embryos exhibit midgestation anemia associated with reduced fetal liver size. (A-F) E12.5 Ccbe1^lacZ/lacZ embryos do not appear paler than littermates and have normal or slightly reduced fetal liver sizes compared with littermate controls. (G-L) E14.5 Ccbe1^lacZ/lacZ embryos appear paler than littermates and have markedly smaller fetal livers that are also pale when compared with littermate controls. (M-R) By E16.5, Ccbe1^lacZ/lacZ embryos are severely pale and have markedly small and pale fetal livers. (S) Midgestation Ccbe1^lacZ/lacZ embryos exhibit severely reduced hematocrits compared with heterozygous littermates on a C57Bl/6 background. Bars indicate mean and standard error of the mean (SEM).