Histochemical study of the efferent nervous system in the guinea pig inner ear

The efferent nervous system of the guinea pig inner ear is histochemically investigated. Remarkable activity of alkaline phosphatase and acetylcholinesterase is demonstrated by Burstone's (1958) azo dye method and Koelle's (1949) method as modified by Gomori (1952) respectively. The distribution pattern of both enzymes in the efferent nervous system is entirely similar. The intraganglionic spiral bundles, fascicles of the osseous spiral lamina and efferent plexus of the organ of Corti reacted intensely for both enzymes. Afferent nerve fibers give no histochemical reaction for both alkaline phosphatase and acetylcholinesterase. However, spiral and vestibular ganglion cells are rich in both enzymes, though they belong to the afferent nervous system. The significance of both enzymes in the nervous system of the guinea pig inner ear is briefly discussed.