Histochemical evidence that cochlear efferents are carried with the inferior vestibular nerve in guinea pigs

Histochemical methods were employed to determine the course of the olivocochlear bundle (OCB) within the vestibular nerve of guinea pigs. Following transection of the inferior vestibular nerve, cholinesterase staining in the cochlea was greatly reduced. Transaction of the superior vestibular nerve, however, yielded no detectable change in staining. It is concluded that the cochlear efferent innervation in guinea pigs is carried in the inferior vestibular nerve, at the point of entry into the medial bulla.