MORPHOMETRIC ANALYSIS OF SATELLITE CELLS IN RAT SKELETAL-MUSCLES - SOLEUS AND EXTENSOR DIGITORUM LONGUS

Satellite cells (SC) are present in all types of skeletal muscles. The y can exhibit DNA replication and mitotic divisions throughout their l ife. Depending on the kind of muscle, a different number of SC is pres ent. The aim of this study was to establish whether the differences in muscle metabolism are reflected in the quantitative ultrastructural e valuation of their SC. Two skeletal muscles of rats, soleus (SOL) with predominant slow fibers and extensor digitorum longus (EDL) with pred ominant fast ones, were studied. Morphometric analysis was performed a ccording to the modified method of Weibel [Stereological Methods, vol 1: Practical Methods for Biological Morphometry. London, Academic Pres s, 1979]. In the SC of EDL mitochondria, rough endoplasmic reticulum a nd Golgi apparatus were less frequent as compared with the SOL. The vo lume fractions of these organelles were much higher in SC of SOL than in EDL. The ribosomes and polyribosomes were more densely packed in SC of SOL than in EDL. Ultrastructural morphometric evaluation demonstra ted significant differences between the SC components of two different muscles: a slow (SOL) and a fast (EDL) one.