Early ultrastructural changes in aging rat gastrocnemius muscle: a stereologic study

Normal gastrocnemius muscle of Wistar rats at various ages to 2 1/2 years was studied. No light microscopic or qualitative electron microscopic changes were seen. However, stereologic determinations revealed significant reductions in volume and surface densities of sarcoplasmic reticulum, t-tubular system, and glycogen content. These alterations were considered to be the morphologic expression of the very early age-related changes in gastrocnemius muscle.