[Histogenetic study of the vestibular ganglion cells in the chick embryo--in relation to the vestibular sensory organs].

The morphogenetic development of the vestibular ganglion cells, nerve fibers and otic vesicle in the chick embryos from 3.5-day-old chick embryos until one day after birth of the chick of White Leghorns was investigated using light microscopy, scanning electron microscopy and lectin's HRP methods. The results were as follows: 1. On the 3.5-day-old chick embryos, the facial-acoustic ganglion mass was located close to the otic vesicle, and on the 4-day-old, it split into the two parts, which the stato-acoustic ganglion at the medial part and the geniculate ganglion at the lateral part. On the 6-day-old chick embryos, the vestibular ganglion and spiral ganglion were completely separated. 2. It was assumed that the stato-acoustic ganglion originated from the otic vesicle, because of its anatomical position and course of development. 3. On the 4-day-old chick embryos, the cell surfaces of the stato-acoustic ganglion on the rhombencephalon side and the geniculate ganglion were labeled with WGA and UEA-1 lectins strongly. This suggested that glycoconjugates were important for histo-differentiation of the stato-acoustic ganglion. 4. Vestibular nerve fibers penetrated lateral wall of the otocyst since the 6-day-old chick embryos until the 8-day-old. (macula of utricle and saccule were seen on the 6 or 7-day-old, and crista of semicircular duct on the 7 or 8-day-old.) And, nerve projection from vestibular ganglion cells to vestibular nuclei was found on the 9-day-old chick embryos. 5. Vestibular ganglion cells were mostly elliptic to spindle shaped with some observed a small sphere by the scanning electron microscopic study. 6. It was estimated that glycoconjugates play the most active development and formation of the vestibular endorgans. And, there was important relation between the formation and development of the vestibular sensory organs and the maturity of the vestibular ganglion cells.