Changes in the Satellite Cell Population during Postnatal Growth of Pig Skeletal Muscle 1

Changes in the proport ion and approximate number of muscle satellite ceils were studied by electron microscopy from 1 to 64 weeks of age in the pig. Transverse sections of the white port ion of the peroneus longus and sartorius muscles were examined in gilts at 1, 2, 4, 8, 16, 32 and 64 weeks of age. The percentage of fibers that contained myonuclei increased with age, while the percentage of nuclei within the basal lamina that were satellite cell nuclei gradually decreased with age. It was concluded that the ultrastructural characteristics and postnatal changes in the satellite cell populat ion of pig skeletal muscle support previous reports for other mammalian species. However, preliminary evidence suggested that the absolute number of satellite cells increased for some time between 1 and 32 weeks of age in the areas sampled in these two muscles. (