Life and Medical Sciences
Wiley InterScience Backfile Collection 1832-2000
Nerve fiber regeneration into sciatic nerve branches was investigated in rats after repairing a 1 cm gap with freeze-thawed autogenous muscle grafts in two configurations. “Prejunctional” grafts were introduced in the main trunk proximal to branching, while Y-shaped “junctional” grafts replaced and reconstructed the site of division of the sciatic nerve into its tibial and peroneal branches. In addition to assessing functional and electrophysiological recovery, myelinated fibers in whole nerve cross sections were counted (i) in the sciatic nerve proximal to the site of transection, (ii) within the grafts themselves proximal to branching, and (iii) in individual tibial, peroneal, and sural branches.Fibers regenerated into all three branches but eventual relative and absolute fiber counts differed between the two graft types, and these in turn from values in these nerves in unoperated controls. Thus, any specific influences directing appropriate fibers into particular branches that might exist did not exert a marked effect on regeneration in vivo. Differences in fiber counts at successively more distal cross-sectional levels were described in terms of elongation, branching, or regression of regenerating fibers. In either graft type, fiber branching coincided with close anatomical relationship with more than one distal stump, and was particularly marked 150-300 days after graft implantation with junctional grafts. However, subsequent penetration of such fibers into the three major branches was more effective if the anatomy of the original branch site was preserved, by using prejunctional grafts. The implications of these findings to clinical nerve repair involving large nerve territories is discussed.
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