Myogenic Shape-Shifters

Apaper in this issue from the laboratory of Guilio Cossu ( De Angelis et al. 1999) is of particular interest because it goes against the grain of what we think we know about two fundamental aspects of muscle biology: first, the embryonic origin of muscle cells; and, second, how damaged muscle repairs itself. Current models indicate that the nuclei in skeletal muscle myofibers originate from the embryonic somites, specifically from the cells located in the dorsal somite epithelium ( Fig. 1 and Fig. 2). Adult skeletal muscle tissue is complex, consisting of multinucleated, contractile myofibers wrapped in connective tissue through which the blood vessels and nerves course ( Fig. 3). Satellite cells are mononucleated cells that reside inside the basal lamina secreted by adult myofibers. When activated through injury, satellite cells initiate stem cell activity and...