Skeletal muscle satellite cell populations in healthy young and older men and women.

The purpose of the present investigation was to assess satellite cell populations and morphology in m. vastus lateralis biopsies obtained from young (20-30 years) and older (65-75 years) healthy, sedentary men and women. Multiple muscle biopsies were obtained from 14 young individuals (men, n = 7; women, n = 7) and 15 older individuals (men, n = 8; women, n = 7). Muscle fibers were viewed longitudinally using a Zeiss EM 10 CA electron microscope. All myonuclei and satellite cells were counted and satellite cells were photographed for morphological analysis. The proportion of satellite cells [satellite cells/(myonuclei + satellite cells)] did not differ among the four subject groups (1.7-2.8%), nor did proportions differ when subject groups were combined for age and gender comparisons. Few morphological differences were noted between groups; however, lipofuscin granules were more prominent in satellite cells from older subjects and women demonstrated significantly larger satellite cell and satellite cell nucleus areas than men. Mitochondria from satellite cells (regardless of group) were more pallid and exhibited fewer cristae than mitochondria located in the adjacent muscle fiber. The results of the current investigation suggest that, despite findings in animal models, satellite cell populations are not significantly lower in healthy, sedentary older compared to young adult men and women. Copyright 2000 Wiley-Liss, Inc.