Acoustic and vestibular efferent neurons in the chicken (Gallus domesticus). A horseradish peroxidase study.

The origin of labyrinthine efferent fibres was investigated in the chicken. After injection of horseradish peroxidase (HRP) into the cochlear duct or into the ampulla of the horizontal semicircular canal, efferent neurons in the medulla oblongata were labelled by the granular reaction product of retrogradely transported HRP. Efferent vestibular neurons were found in the nucleus reticularis pontis caudalis bilaterally with more cells ipsilateral to the injection side, while efferent cochlear neurons could be demonstrated medial to the ventral division of the facial nucleus bilaterally with more neurons contralateral to the injection.