MUSCLE TRANSPLANTATION BETWEEN NORMAL AND DYSTROPHIC MICE. 1. HISTOLOGICAL STUDIES

Minced normal and dystrophic tibialis anterior muscles were transplanted into normal and dystrophic mice in the presence or absence of the peroneal nerve. Transplants were examined at intervals ranging from 0 to over 300 days in normal hosts and 0 to 200 days in dystrophic hosts. In the first 10 days after tranriplantation all muscle minces underwent degeneration followed by proliferation of precursor cells of connective tissue and muscle. By 8 days, myotubes with internal nuclei were abundant. Further differentiation of myotubes into muscle fibres occurred only in normal hosts with an intact peroneal nerve. Transplants in dystrophic mice, and in normal mice in which the peroneal nerves were capped with polydimethyl silicone rubber, underwent progressive degeneration, and by 100 days consisted mainly of connective tissue and fat. In normal hosts innervated dystrophic transplants were histologically similar to auto‐ and homotransplants of normal muscle. A significant population of regenerated fibres in normal and dystrophic transplants showed internal nuclei, variation in size and splitting, and were smaller in diameter than those from intact normal muscles. Since normal and dystrophic transplants failed to survive in the dystrophic hosts and in the denervated state in normal mice, it is suggested that the failure of dystrophic mice to maintain minced muscle transplants may be due to an inherent inability of dystrophic nerves to establish functional neuromuscular contact with these transplants.