ANATOMICAL AND PHYSIOLOGICAL-CHARACTERISTICS OF THE VESTIBULAR GANGLION OF THE BULL FROG

The spatial distribution of nerve fibers from individual Vestibular en d organs in the vestibular ganglia (VG) was studied using horseradish peroxidase (HRP). HRP was injected into the cut end of the bull frog a mpullary nerve. Stained neural elements were counted on the serial sec tions. Spatial distribution was also studied by recording ampullary ne rve compound action potentials (AP) from VG. The anterior semicircular canal (SC) nerves were distributed in the anterior half of VG. The ho rizontal SC nerves were also distributed in the anterior half of VG, b ut tended to be posterior. The posterior SC nerves were found predomin antly in the posterior half and antero-dorsal portions. These distribu tion patterns corresponded well with those confirmed by AP recording. There were a few neural connections between anterior and posterior SC, or horizontal and posterior SC, indicating receptor-receptor fibers.