Effects of predegeneration on nerve regeneration through silicone Y-chambers.

The effects of nerve predegeneration on the preferential growth of regenerating axons were studied using a silicone Y-chamber model. This system provided a choice for axons to grow towards two distal nerve options, either a 7-day predegenerated nerve segment (PNS) or a fresh nerve segment (FNS). The rat peroneal or tibial nerve was inserted into the proximal intlet and the PNS and FNS of the corresponding nerve were inserted into the distal outlets. At 28 days postoperative, the size of the distal regenerate was significantly greater (26%) towards the PNS for the tibial nerve group. The density and number of regenerated myelinated axons in the distal nerve segment was greater on the PNS for both the tibial (97 and 88%, respectively) and peroneal (221 and 221%, respectively) nerve groups. In contrast, the elevated density and number of nonvascular nuclei was relatively constant for both PNS and FNS. Immunocytochemical and ultrastructural evidence support the hypothesis that the early activation of Schwann cells is primarily responsible for the enhanced regeneration and maturation observed in PNS. It is suggested that PNS might improve the outcome after clinical repair of injured peripheral nerves.