Dynamics of regeneration in skeletal muscle following localized heat injury

Local heat applied to rat skeletal muscle determines sudden and brutal necrosis followed by a process of regeneration which develops in a continuous and discontinuous mode. The complex cytohistological and histochemical modifications have been simultaneously followed up. Results may be summarized as follows: during the first 6 to 70 hours after heat application, a morphologica disorganization occurs at the level of both muscle fibers and muscle intertice. Protein reactions are very low or negative within this interval of time. After 10 days, at the site of the injury there appear regenerative elements: young muscle cells, mononucleated cells (myoblasts) and polynucleated myotubes (sarcoblasts). At the level of these formations and of muscular buds in the regenerating zones the histochemical reactions turn positive. Af 35 days after injury the damaged muscle fibres are reconstructed and the intensity of histochemical reactions equals that in the control. Results are indicative of the unity between reactivity of the morphologicall organized cell structure and that of the protein substrate.