COMPARISON BETWEEN GRAFTS WITH INTACT NERVES AND STANDARD FREE GRAFTS OF THE RAT EXTENSOR DIGITORUM LONGUS MUSCLE

Abstract

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 fiber degeneration and regeneration as standard grafts. In nerve-intact grafts, the intramuscular portions of the nerve fibers initially degenerated, but within 1 wk new nerve fibers 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 2nd wk 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.