FUNCTIONAL AND STRUCTURAL RECOVERY OF MYOTUBES FROM MICE WITH MUSCULAR DYSGENESIS AFTER COCULTURE WITH NORMAL, NON-MYOBLASTIC CELLS

Muscular dysgenesis is a mutation which is characterized by paralysis of skeletal muscle cells. Excitation-contraction coupling is deficient and muscle cells display atypical ultrastructure. In vitro, mutant my otubes recover a normal phenotype when cocultured with spinal cord cel ls from normal animals or with normal fibroblasts. We have shown that other types of cells, eg certain glial cells present in the spinal cor d or in other tissues, have this capacity. In contrast, intervention o f neurons in the recovery does not appear likely. Very different types of non-myoblastic cells, then, are capable of restoring contractile a ctivity of dysgenic myotubes in vitro, suggesting that a non-specific mechanism is involved in the phenotypic reversion of affected muscle c ells. The restoration process seems to imply a close relationship betw een myotubes and normal glial cells.