Neurotropic influence of the distal stump of transected peripheral nerve on axonal regeneration: absence of topographic specificity in adult nerve.

Observations have been made on the growth of regenerating axons from transected rat sciatic nerve through Y-shaped silicone tubes. When the distal stump of the nerve was sutured into 1 distal limb of the tube and a fat pad into the other, a clear preference for the axons to regenerate towards the distal stump was found. In other experiments regenerating axons from the peroneal or tibial divisions of the sciatic nerve were given the choice of growing towards either the peroneal or tibial nerves, each being inserted into 1 of the 2 distal limbs of the Y-tube. No significant preference of the proximal stump to regenerate towards its appropriate distal stump was detected. A neurotropic influence of the distal stump on the nerve has therefore been confirmed, but topographic specificity of regeneration at the level of the nerve trunk has not been established.