Cross-reinnervation of dystrophic mouse muscle

Transplantation of extensor carpi radialis longus muscle in normal and dystrophic chicks

The etiology of avian muscular dystrophy was examined by a cross-transplantation technique. Care was taken for the transplants to regenerate and develop under neural influence, by using the small extensor carpi radialis longus (ECRL) muscle. The ECRL muscles were exchanged between normal and dystrophic chicks 2 to 3 days ex ovo, and the muscle weight, number of muscle fibers, muscle fiber size, and contractile properties of the transplanted muscles were observed 60 to 65 days after operation when the tissue reconstitution was virtually complete. The results obtained for the physiologic, anatomic, and histologic parameters strongly suggested that there exists some failure in the host environment of the dystrophic chicken. The analyses of the histologic parameters suggested that a genetic disorder may also reside in the muscle tissue itself. The myotonic nature of the muscle membrane, however, probably does not contribute significantly to the abnormal behavior of dystrophic chickens. The importance of some neurogenic abnormalities in avian muscular dystrophy is discussed in relation to the results reported by other investigators.

Parabiotic reinnervation in normal and dystrophic mice. Part 1. Muscle weight and physiological studies

A technique called parabiotic reinnervation has been developed. This technique consisted of suturing the sectioned peripheral end of the common peroneal nerve of a normal mouse, strain 129 ReJ +/+ to that of the distal stump remaining after sectioning that same nerve in a dystrophic mouse, strain 129 ReJ dy/dy. The animals were then parabiosed and allowed to recover and thus it was possible to innervate a dystrophic muscle with a normal nerve and vice-versa. This made it possible to test the hypothesis that a derangement of the trophic function normally exerted by a nerve on a muscle might be an element in the pathogenesis of muscular dystrophy in the adult mouse. Studies on the weights and isometric twitch characteristics of such parabiotically reinnervated muscles led to the conclusion that a derangement of the trophic function exerted by a nerve on a muscle is not an element in the pathogenesis of muscular dystrophy in the adult 129 ReJ dy/dy strain of mouse.

Physiological estimates of the sizes and the numbers of motor units in soleus muscles of dystrophic mice

Evidence is presented to support the neurogenic hypothesis for murine dystrophy. Axonal atrophy, decrease in twitch tensions of individual motor units and loss of motor units suggest that "sick" motor units are present in dystrophic mice and that the "sick" motor units were once functional, but had gradually degenerated, possibly due to a neurotrophic deficiency.