Red blood cell selection in chimeric mice

Starch gel electrophoresis of a large number of tissues and organs from C3H in equilibrium C57BL aggregation chimeras suggests that the C57BL red blood cell population predominates, whereas for other tissues the proportions of the two components are more nearly equal. A similar predominance of (C57BL X C3H)F1 red blood cells is seen in (C57BL X C3H)F1 in equilibrium Recessive chimeras. Analysis of blood samples taken from the same animals at different times suggests that a temporal shift in the proportions of the two component red cell populations occurs in some adult chimeras and results in an unbalanced chimeric phenotype. It is suggested that differential mitotic activity contributes to strain-dependent, tissue-specific selection pressures in the erythropoietic tissue.