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Regeneration of muscle in Duchenne muscular dystrophy: An electron microscope study

Mastaglia, F.L., Papadimitriou, J.M. and Kakulas, B.A. (1970) Regeneration of muscle in Duchenne muscular dystrophy: An electron microscope study. Journal of the Neurological Sciences, 11 (5). pp. 425-444.

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Electron-microscopic observations have been made on skeletal muscle from cases of Duchenne muscular dystrophy and particular attention has been paid to the regenerative changes. The degenerative changes encountered were similar to those which have been found by previous workers. The most basic change was a segmental one and consisted of supercontraction of myofibrils which appeared to precede their fusion and subsequent breakdown. It is suggested that the supercontraction may represent a state of contracture or failure of relaxation due to a relative deficiency of ATP in the muscle fibre.

Regenerative changes were found in considerable numbers of muscle fibres particularly in the younger cases. In fibres showing advanced degenerative changes, “satellite cells” were commonly found to be enlarged and to have a more elaborate organelle content than that of the resting “satellite cell”. Thin filaments were found in the cytoplasm of some “satellite cells” confirming their ability to differentiate into myoblasts. Ribosomal aggregates were found within the degenerate sarcoplasm of some fibres but were not associated with new filament formation.

Regenerating fibres were recognized by the presence of polyribosomes in the sarcoplasm and large nuclei with dispersed chromatin and prominent nucleoli. Although in some fibres the pattern of myofibrillar development appeared to be quite normal, in many regenerating fibres the myofibrils were poorly aligned and at times completely disorganized and often showed abnormalities such as streaming of the Z-band or other focal deficiencies in isolated sarcomeres. Mitochondria were sparse in the vicinity of developing myofibrils. In some small fibres which ended blindly, regenerative changes appeared to have become arrested.

The present observations indicate that although dystrophic muscle is capable of regeneration, the pattern of morphological development of the contractile elements in regenerating fibres is often abnormal. Moreover, there is evidence of metabolic abnormalities in such fibres. The observed abnormalities in the regeneration of dystrophic muscle correlate with the known abnormal growth pattern of dystrophic muscle in tissue culture. The possible reasons for these abnormalities are considered.

Publication Type: Journal Article
Publisher: Elsevier BV
Copyright: © 1970 Elsevier B.V.
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