Histometric and electron cytochemical study of muscle in the dystrophic mouse.

A histometric analysis of the alterations at the motor end plate in dystrophic Bar Harbor mice has been performed. In both forms of mouse dystrophy, simplification and focal atrophy of the junctional folds and retraction of the nerve terminal represented the significant changes. The postsynaptic alterations were similar to those described in Duchenne dystrophy. In constrast, the presence of presynaptic alterations in these mice indicated the presence of both a neural and a muscular abnormality. The wedge-shaped focal lesions in the muscle of dystrophic mice were demonstrated by both in vitro and in vivo HRP tracer techniques. These focal degenerative changes in muscle were similar to those described in Duchenne dystrophy. Employing the technique of extracellular space tracing, a comparison was made of the appearance of the transverse tubular system in the various types of dystrophic muscle fibers.