THE IMPACT OF A MUSCLE TARGET ORGAN ON NERVE GRAFTS WITH DIFFERENT LENGTHS - A HISTOMORPHOLOGICAL ANALYSIS

The present study was done in order to evaluate the influence of a tar get muscle on the regenerative processes in long nerve grafts. In 21 r abbits the saphenous nerve was used as a nerve graft and coapted to th e cut motor nerve of vastus media(is. The animals were separated into three groups with different graft lengths, namely 3, 5, and 7 cm. In a second stage the distal end of the graft (Graft.dist.) was coapted to the motor branch of rectus femoris. Cross sections of the normal vast us nerve and the Graft.dist, before and 7 months after the connection to rectus femoris were analyzed histomorphometrically. Before coaptati on to the target organ mean fiber number in the Graft.dist. of the 3-c m-long grafts was 3380 and decreased to 2413 in the 7-cm-long grafts. Seven months after coaptation the results showed a statistically signi ficant decrease of fibers in the Graft.dist. of group two and three an d a distinct decrease of the fibers in group one. Summarizing, in a tw o-stage nerve grafting procedure the reinnervation of the muscle targe t organ leads to a down-regulation of fiber's in the distal end of sho rt and long nerve grafts. (C) 1998 John Wiley & Sons, Inc.