MDX mouse myopathy I: Presence or absence of sarcolemmal lesions in tibialis anterior muscles from mice of different ages
Since the ‘mdx’ mouse appears to have the same basic defect as sufferers of human Duchenne Muscular Dystrophy (DMD), much recent interest in this possible animal model for the human disease has been generated. Perforations in the sarcolemma have been reported recently in the necrotic tibialis anterior (TA) of 35-days-old and the extensor digitorum longus muscles of 39-days-old ‘mdx’ mice. It is the purpose of this communication to find out if these lesions occur not only in necrotic, but also in unaffected, or in centronucleated fibers of the TA of mice which are younger than 35, or older than 39 days.METHODS: TA from 22-, 25-, 41-, 61- and 99-days-old C57BL/10ScSn/MDX and C57BL/lOScSn control mice were pinned on corkboard in a relaxed state, prefixed for 30 minutes in 2.5% glutaraldehyde followed by routine processing for TEM. Appropriate micrographs were evaluated for a more detailed morphological analysis of the sarcolemma (SL) and the basal lamina (BL).RESULTS: It should be stated beforehand that in all muscles examined the BL appeared to be intact. In the muscles of a 25-days-old control mouse the SL appeared quite intact (FIG. 1). In contrast to this small perforations or large tears in the SL could be seen in otherwise unaffected muscles of 22- (FIG. 2), 25- and 41-days-old ‘mdx’ mice, as well as in necrotic and regenerating fibers of mice from these ages.