Comparison between grafts with intact nerves and standard free grafts of the rat extensor digitorum longus muscle

Standard grafts and nerve-intact grafts of the extensor digitorum longus muscle were compared in the rat. In standard grafts the muscle was completely removed from its bed and replaced; nerve-intact grafts were treated in an identical manner except that the muscle nerve was not severed. Nerve-intact grafts underwent the same sequence of skeletal muscle fibre degeneration and regeneration as standard grafts. In nerve-intact grafts the intramuscular portions of the nerve fibres initially degenerated, but within a week new nerve fibres had regenerated back to the original zone of motor end-plates. By 60 days the weight of nerve-intact grafts approached those of control muscles. Contractile tension in nerve-intact grafts was greater than that of standard grafts. In standard and nerve-intact grafts choline acetyltransferase activity rapidly decreased to low values and then increased along curves roughly paralleling the muscle weights. In nerve-intact grafts, neuromuscular transmission was established early in the second week whereas a considerably later return was seen in standard grafts. Either the early onset or the topographical pattern of reinnervation are potentially major factors in determining the success of free muscle grafts.