Specificity of muscle reinnervation after epineurial and individual fascicular suture of the rat sciatic nerve.

We experimentally analyzed the specificity of muscle reinnervation after suture and regeneration of rat sciatic nerve. We used a horseradish peroxidase (HRP) technique of axon tracing to compare the number and location of motoneurons that innervate muscle via the peroneal nerve after epineurial and individual fascicular suture of the parent sciatic nerve. These motoneurons are significantly reduced in number from control levels and are often in spinal cord locations that indicate previous innervation of antagonistic muscle via the tibial nerve. This inappropriate reinnervation of peroneal muscle by tibial motoneurons is minimized by individual fascicular suture without compromise of overall reinnervation. Our findings thus support the hypothesis that individual fascicular suture may avoid distortion of the central connections of peripheral units.