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Publisher Summary This chapter discusses the problems of reinnervation of muscle. The implications of electron microscopical descriptions of the synapses on the possibilities of changes in connectivity are discussed. The changes in axon and myelin thickness above lesions in peripheral nerve are described and are related to electron microscopical changes. The capacity of muscle fibers to accept more than one motor endplate is discussed and the experiments in which foreign nerves are implanted in the diaphragm and the infrahyoid muscles are described. New motor endplates can be recognized by their ectopic positions. When the original endplates are available in a denervated muscle the invading nerves will search them out and reoccupy them. Only when the original endplates have been excised or destroyed, the new endplates will develop. Combined silver and cholinesterase techniques have shown the nerve fibers in the new endplates. In the diaphragm, the intercostal nerve reinnervated the original endplates and contraction of the diaphragm on the operated side is synchronous with the intact side. The extent of the reinnervation varied with the length of time allowed for the intercostal nerves to grow into the diaphragm. The absence of phrenic reinnervation is confirmed in each experiment. |
