Anatomical Distribution of Efferent Fibers in the Viiith Cranial Nerve of the Bullfrog (Rana Catesbeiana)

Abstract

The VIIIth cranial nerve of the bullfrog was surgically transected between the brain stem and sensory ganglion. Two to three weeks after section of the nerve the frogs were sacrificed and the Wallerian degeneration in the nerve was studied. It was possible to demonstrate the presence of efferent fibers going toward the sensory epithelium of all the recognized vestibular end-organs, and also toward the papilla of the pars amphibiorum. However, no efferent fibers were seen at the level of the papilla basilaris. The ganglion cells of both the acoustic and vestibular afferent fibers appeared normal. Many degenerated fibers were seen around the sacculus wall among a group of fibers previously undescribed.