RESUMO
The authors described the reconstruction of a terminal branch of the brachial plexus (the median nerve) by different kinds of peripheral nerve grafts, in rats. Fresh or frozen autografts from Sprague-Dawley rats and fresh or frozen xenografts from Beagle dogs were used. Three, six, nine and twelve months after grafting, rats underwent histological assessment (muscle, nerve and spinal cord) and simple functional assessment by the grasping test. The immune reaction was prevented by the freezing and thawing method that had rendered xenografts acellular. This process allowed a satisfactory reinnervation of the flexor carpi radialis muscle (FCR) and a function recovery about 75% of control value. Nevertheless, the force recovery in rats that received frozen grafts was slower than those received fresh autografts. Probably, the destruction of cellular elements by freezing produced a deficient environment for nerve regeneration. However, this gap was partially compensated at twelve months after surgery by the maturation and the secondary adaptation of regenerated nerve fibers. Theses results showed that the force recovery is directly correlated to the capability of the nerve fibers to reproduce, histologically, a next to normal nerve pattern.
