Experimental studies on the role of satellite cells in regeneration of rat skeletal muscle fibers.

The process of degeneration, necrosis and regeneration of skeletal muscle fibers of rats administered dimethyl-para-phenylenediamine was studied by light and electron microscopy. Electron microscopy revealed satellite cells between the basement membrane and plasma membrane of unaffected as well as affected muscle fibers. The cytoplasm of satellite cells was enlarged or elongated and contained many ribosomes, polysomes, rough-surfaced endoplasmic reticulum and well-developed Golgi apparatus. In some satellite cells myofilaments were formed attached to the ribosomes and polysomes. In the process of muscle regeneration many myogenic cells appeared in the vicinity of unaffected muscle fibers. The properties of the cytoplasmic organelles of the myogenic cells resembled those of satellite cells. The differentiation between satellite cells and myogenic cells could be made only by the presence or absence of preexisting muscle fibers. From these results it is not only suggested that the satellite cells are the precursor of myogenic cells but also the regenerated muscle fibers, at least a part of them, originate from satellite cells.