Protection from Haemopoietic Death by Shielding Versus Grafting of Bone-marrow

Summary

In an attempt to clarify the conflicting data in the literature, the efficacy of shielded bone-marrow cells versus injected bone-marrow cells for haemopoietic restoration of lethally-irradiated mice was reinvestigated. Three different end-points were employed. Spleen-weight at 10 days after irradiation was used instead of spleen-colony count, because of the difficulty encountered in enumeration of endogenous spleen colonies. Repopulation of the unshielded femur at day 10 after irradiation was used as a second end-point, since the colonization pattern of endogenous surviving cells might be directed to parts of the haemopoietic system other than the spleen. As a third end-point, 30-day survival of lethally-irradiated animals was used, which required a two-phase irradiation to avoid changes in mortality pattern caused by the immobilization during irradiation. The results obtained by all three methods indicate that endogenous surviving cells are at least equally effective in repopulating the haemopoietic tissues as grafted bone-marrow cells.