Termination of the Olivo-Cochlear Bundle in Relation to the Outer Hair Cells of the Organ of Corti in Guinea Pig

Abstract

A. Section of the olivo-cochlear bundle at the facial colliculi area in the guinea pig produced the following results:

1. Many large granulated nerve endings, type 2, were found consistently degenerated. They are the ultimate terminals of the crossed olivo-cochlear bundle in efferent nature.

2. A considerable number of large granulated nerve endings were left intact on the outer hair cell. They may be the terminals of the homolateral fibers of the superior olivary complex, or of some other origins.

3. The outer sensory cell showed some changes.

4. The tunnel spiral bundle carried some of the crossed efferent cochlear fibers.

5. Basal turn showed more degenerative large nerve endings than higher turns.

6. Small nerve endings remained normal, or affected some degree secondarily to the disintegration of the adjacent large nerve endings.

B. Section of the auditory nerve at the internal auditory meatus demonstrated degeneration of small nerve endings and atrophie changes in spiral ganglia. The small nerve endings are afferent terminals.