Muscle fiber regeneration in nerve-intact and free skeletal muscle autografts in cats

Extensor digitorum longus (EDL) muscles of adult cats were transplanted as free autografts (FRA) with the nerve severed or as nerve-intact autografts (NIA) with the nerve retained. Histochemical and contractile properties of NIA and FRA were analyzed at selected times from 1 to 14 wk after surgery. Regeneration was qualitatively similar in NIA and FRA. Regenerating fibers were observed in both NIA and FRA within 2 wk. After 14 wk there were fewer type I fibers in both NIA and FRA than in control EDL muscles. Capillarity was greater in NIA than FRA, but both types of autografts had significantly reduced capillarity relative to control muscles. Mean fiber area, muscle mass, and absolute tension development were greater in NIA than FRA but did not reach control muscle values. Muscle mass, mean fiber area, and contractile properties, but not the proportion of type I fibers, develop toward control values more quickly in autografts with the nerve left intact.