RELATIVE ABILITY OF PARENTAL MARROWS TO RE-POPULATE LETHALLY IRRADIATED F1 HYBRIDS

The relative abilities of C57BL and 101 marrow to repopulate the hematopoietic system of lethally x-irradiated mice was determined. The disproportionately greater ability of 101 than C57BL cells to repopulate (C57BL X 101) F/sub 1/ recipients is reported, and data are given on the relative ability of marrow from other strains of mice to repopulate lethally irradiated mice. Consistent with the observation that C57BL marrow is less efficient that 101 marrow is the finding that the number of C57BL cells required to produce functioral long-terra marrow grafts was much larger than the number of 101 cells. Factors that might influence the differential in the growth ability of the two types of marrow are discussed. (H.M.G.)