Transplantation of human skeletal muscle to nude mice: a sequential morphologic study.

Normal human quadriceps muscle was transplanted into nude mice subcutaneously for periods of 1, 2, 3, 4, 6, and 8 weeks. At 1 week, there was myoblast and myotube formation with thin and thick filaments. After 2 weeks, there was myotube formation with partially cross-striated myofilaments, and formation of dyads or triads. Leptomeres were also noted in some myotubes. By 4 weeks, cross-striation of myofilaments and migration of muscle nuclei to the periphery were observed. Distended sarcoplasmic reticulum and honeycomb structures of tubules were noted between 4 and 8 weeks. This study indicates that mature human muscle can be transplanted successfully into nude mice, providing another tool for the investigation of human neuromuscular disease.