The dependence of nerve regeneration through muscle grafts in the rat on the availability and orientation of basement membrane.

Nerve regeneration through grafts of basement membrane matrix, prepared by freezing of autogenous muscle followed by thawing in distilled water, was investigated in Sprague-Dawley rats. Electrophysiological evidence of recovery in distal nerve was observed at 51 days after implantation of treated grafts whose basement membrane tubes were coaxial with the proximal and distal ends of the transected sciatic nerve. This correlated with histological findings of well-developed myelinated nerve fibres within both grafts and distal nerve. However, whereas normal axon numbers were achieved in the grafts by 3 months, the regenerating nerve in these muscle grafts took 6 months to 1 year to recover normal axon diameter and myelination. Recovery was delayed through grafts whose basement membrane tubes were at right angles to the nerve fibres and through grafts of untreated muscle coaxially aligned. It is concluded that successful repopulation of the distal stump and functional recovery can follow nerve regeneration through treated muscle autografts. The rate of regeneration is dependent on the availability of empty basement membrane tubes. If these are unavailable or inappropriately orientated, regeneration can still occur but is significantly delayed.