Ultrastructure of muscle spindles in dystrophic mice

Abstract

ALTHOUGH the pathological changes in muscular dystrophy are commonly attributed to a primary abnormality of the muscle fibres, there is evidence to suggests that mucular dystrophy may be attributable to a neuronal abnormality¹. This has become known as the ‘neural hypothesis’. Dystrophic mice (Bar Harbor 129 REJ dy/dy) provide a useful model of muscular dystrophy for experimental study. In spite of the early onset of abnormal reflexes in muscular dystrophy, the richly innervated sensory organs, muscle spindles, have received relatively little attention^2,3. Optical microscopical studies have indicated that spindles in dystrophic mouse muscles are essentially unaffected⁴, although in some human diseases they seem to undergo minor changes⁵. This study was undertaken to establish whether there are ultrastructural changes in spindles of dystrophic mice which are detectable only by electron microscopy.