[Stromal precursor cell count in the bone marrow of young and old CBA mice]

The content of stromal precursor cells in the bone marrow of young (1-4-month-old) and old (24-30-month-old) CBA mice was measured by cloning in primary monolayer cultures. It was found that both the concentration (fibroblast colony forming efficiency) and the total number of stromal precursors in femoral bone marrow markedly increased with aging.