Interaction between foreign and original nerves innervating gill muscles in fish.

Foreign somatic motor nerves were made to innervate denervated gill muscles of the perch. The foreign innervation remained functional after reinnervation by the original nerve. Intracellular recordings showed that individual muscle fibers could be activated by both foreign and original neurons. Extensive foreign innervation appeared to inhibit the ability of the original nerve to reinnervate its own muscle. These studies provide evidence for a functional coexistence of appropriate and inappropriate innervation and show that foreign synapses need not be repressed by the "correct" nerve.