Direct muscle neurotization in rat soleus muscle.

An experimental study was conducted using rat soleus muscles to characterize reinnervation of the denervated muscles by direct muscle neurotization. Also studied was whether there is any difference in the regeneration process between original (tibial) and foreign (peroneal) nerve neurotization. For functional evaluation, an electrophysiologic study was carried out by analyzing pattern, latency, amplitude, and duration of compound motor action potential. In a histochemical study, both hematoxylin-eosin stain and nicotineamide adenin dehydrogenase stain were used to identify the morphology and the change in the type of muscle fiber. Combined silver-acetylcholinesterase stain was utilized to identify reinnervated motor endplates and axonal sprouting. Evidence of regeneration of the denervated muscle by direct muscle neurotization could be confirmed. Regenerating muscles showed type grouping of muscle fibers. The newly-formed ectopic motor endplate was connected with axonal sprouting. The giant motor endplate composed of mature axon sprouting and several new ectopic motor endplates appeared in the neurotization group. There was no specific difference in the regeneration process between original and foreign nerve neurotization.