Bone marrow cells of mice under the influence of low lead doses.

The influence of lead on the number of nucleated bone marrow cells and pluripotent stem cells in femur bone marrow was investigated in mice. It was found that neither a single nor 10 days' oral administration of lead at doses of 10-1,000 micrograms PbAc/kg b.w. led to any change in the bone marrow cellularity. After 1 month's oral administration of 1,000 micrograms PbAc/kg b.w., on the other hand, there was a significant reduction of nucleated bone marrow cells and pluripotent stem cells in the femur bone marrow of up to 20% in comparison with controls. Within 14 days after completing the lead administration, however, normal values in the bone marrow cellularity were found again. Three months' oral administration of lead at doses of 100 and 1,000 micrograms PbAc/kg b.w. led to a significant reduction in nucleated bone marrow cells and pluripotent stem cells in the femur bone marrow of up to 28% compared with the controls. In contrast to the experiments with 1 month's oral administration of lead the regeneration of the bone marrow was not completed 14 days after completing the administration of the lead. These results show that lead at doses above 100 micrograms PbAc/kg b.w. causes on long-term administration a clear reduction of the nucleated bone marrow cells combined with a depressed regeneration ability of the pluripotent stem cells.