Topographical reinnervation of the toad glutaeus muscle by axons of only one spinal nerve.

The toad glutaeus muscle is innervated by axons from two spinal nerves. Following regeneration from nerve lesion, axonal reinnervation from both spinal nerves remains topographically selective. The aim of the present experiments was to determine whether axons from one spinal nerve (nerve 9) would topographically reinnervate the glutaeus muscle in the absence of innervation from the other spinal nerve (nerve 8). Glycogen depletion of single motor units showed that nerve 9 axons are topographically selective when reinnervating the muscle alone. The synapses formed are stronger in topographically correct locations even in the absence of nerve 8 innervation. The distinction between the territory innervated by rostral and caudal nerve 9 axons arises independently of the presence of nerve 8 axons.