Peripheral vestibular organ ; Vestibular afferent nerve ; Central projection ; Vestibular nucleus
Abstract
The central projections from each peripheral vestibular organ in mongolian gerbil were investigated by applying horseradish peroxidase extracellularly after scratching each crista and macula. Neuroepithelium of each crista and macula was scratched selectively with and electrolytically sharpened fine needle and the vestibule was filled up with 30% horseradish peroxidase solution. Forty eight hours after applying HRP, 100㎛ serial sections of brain stem were made. The tissue was processed for histologic examination with the diaminobenzidine procedure of cobalt-glucose oxidase method.
The primary afferent fibers from the superior semicircular canal projected to the entire area of superior vestibular nucleus, ventral and dorsal part of lateral vestibular nucleus, rostral end of descending vestibular nucleus, rostro-dorsal part and caudo-ventral part of medial vestibular nucleus. The fibers from the lateral semicircular canal projected to the lateral part of superior vestibular nucleus, ventro-lateral part of lateral vestibular nucleus, ventral part of descending vestibular
nucleus, dorsal and ventral part of rostral medial vestibular nucleus. The fibers from posterior vestibular nucleus projected to the dorso-lateral part of superior vestibular nucleus, medial part of rostral end of descending vestibular nucleus, rostro-dorsal part and caudo-ventral part of medial vestibular nucleus, and interstitial nucleus. The fibers from the utricle projected to the lateral part of superior vestibular nucleus, ventral part of lateral vestibular nucleus, lateral part
of descending vestibular nucleus, rostro-central part and caudo-dorsal part of medial vestibular nucleus. The fibers from the saccule projected to the periphery of superior of superior vestibular nucleus, lateral part of lateral vestibular nucleus, entire area of descending vestibular nucleus, ventral and dorsal part of rostral medial vestibular nucleus, interstitial nucleus, and group Y. Above results suggest that all the major vestibular nuclei except the lateral vestibular nucleus are functionally related to all of each peripheral vestibular organ and different informations form each peripheral vestibular organ transfer to each specific areas in the major vestibular nuclei. To clarify the functional significance of these results, the further study of the upper central pathways and neurophysiological study related to the vestibular reflex arcs will be needed.