Postnatal Development of the Structure of the Peripheral Vestibular System of the Gerbil

抄録

Postnatal development of the peripheral vestibular system and surrounding components in the gerbil was studied to obtain topological information for electrical vestibular stimulation. At postnatal day 1, the peripheral vestibular nerve had already reached the vestibular apparatus. The central vestibular nerve extended posteriorly to enter the brainstem at a sharp angle to anterior-posterior axis. During development, the vestibular ganglion was progressively displaced caudally, along with the vestibular nerve and the ventrally located facial nerve, increasing the angle to the anterior-posterior axis to nearly 90° by postnatal day 30. Contact between the anterior part of the vestibular ganglion and the facial nerve, and that between the posterior part of the ganglion and the cochlear nerve were observed at all ages. These regions were considered unsuitable for electrical stimulation because of the high risk of stimulating the facial or cochlear nerve, similar to those regions in the adult. These results as well as the observation that the diameter of the lateral semicircular canal remained nearly constant showed that the technique we used for electrical vestibular stimulation in adult animals was apparently a good choice in younger animals as well.