Abstract
A study has been made of the distribution of 239Pu in the bone marrow and on the endosteal bone surfaces of adult rabbits following both the intramuscular and intravenous injection of 239Pu(NO3)4. Differences in the marrow distribution can probably be attributed to differences in the colloidal character of the plutonium reaching the marrow, depending on the rout of injection. Examination of the distribution of the 239Pu, as seen in the heavy band of α tracks on the endosteal surface both of the bone after removal of the marrow and on the extruded marrow, showed that approximately 40 per cent was present in or on the endosteal cells and 60 per cent was present on the mineral or matrix of the bone surface free of cells. The amount of 239Pu in the endosteal cells varied in a similar manner with time after injection to the amount of 239Pu on the mineral surface. The presence of 239Pu in the osteogenic cells themselves may account for the great carcinogenicity of this radionuclide.