[Stereologic ultrastructural and cytochemical study of myocardial hypertrophy during gerontogenesis].

The myocardium of male Wistar rats aged 4, 24 and 33 months was examined using stereological techniques to determine the volume and surface densities of the ultrastructure of cardiac myocytes. Electron microscopy was used to detect succinate dehydrogenase in mitochondria. The myocardium of senescent animals was shown to be hypertrophied. The ratios of the volume densities of mitochondria, sarcoplasmic reticulum and T-system to the volume density of myofibrils in cardiac myocytes considerably decreased with age. The activity of succinate dehydrogenase in mitochondria reduced as well.