NERVE REGENERATION ACROSS A 25-MM GAP BRIDGED BY A POLYGLYCOLIC ACID COLLAGEN TUBE - A HISTOLOGICAL AND ELECTROPHYSIOLOGICAL EVALUATION OF REGENERATED NERVES

In the study reported here we have examined the nerve regeneration tha t occurs over a 25-mm gap using a novel biodegradable nerve guide tube . The tube was a composite of polyglycolic acid (PGA) mesh coated with collagen which was filled with neurotrophic factors. The left sciatic nerve of ten adult cats was dissected. The stumps were connected by t he tuber and fixed gap. Histological examinations carried out 4-16 mon ths after implantation of the tubs revealed regeneration of well vascu larized nerve tissue. Regeneration of both myelinated, unmyelinated ax ons and Schwann cells was confirmed by electron microscopy 5 months af ter surgery. Following injection of horseradish peroxidase (HRP) into a site peripheral to the regenerated segment of the sciatic nerves, mo toneurons in the ventral horn of the spinal cord, afferent terminals i n the medial portion of the dorsal column of the medulla oblongata, an d sensory afferent nerve terminals in the dorsal horn of the spinal co rd were labelled. Electrophysiological examinations revealed restorati on of evoked electromyograms and sensory evoked potentials (SEPs) reco rded from the cerebral cortex as well as the spinal cord. We also foun d that some of the regenerated motor axons exhibited branching in the regenerated segments. In two cases, a single motoneuronal axon from th e regenerated side projected to both flexors and extensors. simultaneo usly. Our results indicate that the PGA-collagen composite tube is a p romising tool for use as a nerve guide tube in peripheral nerve regene ration.