AN INVESTIGATION OF THE INFLUENCE OF THE EXTRACELLULAR ENVIRONMENT ON THE REGENERATION OF THE NORMAL AND DYSTROPHIC MOUSE MUSCLEIN VITRO

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Abstract
The regenerative response of normal and dystrophic muscle cultured with fetal spinal cord was investigated. Nearly all the normal muscle explants regenerated. The dystrophic muscle gave a much more varied response; only 30% regenerated and 38% showed total explant degradation with loss of all recognizable muscle elements. Of the dystrophic explants, 45% produced pseudostraps with an apparent block of myoblast fusion. Cultures in which cellular contact between spinal cord tissue and the normal or dystrophic muscle was prevented showed less regeneration than when it was allowed. The incidence of regeneration in these cultures was much higher than when the muscle was cultured in isolation. Direct cellular contact between the cord and the muscle apparently is not necessary to initiate regeneration which is presumably mediated in these cultures by changes in the chemical environment. This is substantiated by the almost complete absence of regeneration in cultures only of muscle, where the fibers were devoid of nuclei within 5 days. Under these conditions a myogenic defect apparently occurs in the dystrophic muscle. A possible neuronal involvement in the etiology of the disease is not excluded, but no evidence was found.