Vestibular Ganglion Cells in Developing Chick Embryo

The morphologic development of the vestibular ganglion and nerve and otic vesicle in the enbryos of White Leghorn chicken was studied n chick embryos from 3.5 days of age up to one day after hatching. In 3.5-day-old chick embryos, the seventh and eighth aranial nerve ganglia appeared as a single facial-acoustic ganglion mass near the otocyst. In 4-day-old chick embryos, a facial-acoustic ganglion mass was divided into the two parts, the primitive stato-scountic ganglion medially and the primitive geniculate ganglion laterally. The vestibular and spiral ganglia from the stato-acoustic ganglion were competely separated in 6-day-old chick embryos. Penetration of vestibular nerve fibers into the sensory area of the otocyst took place in chick embyos incubated during 6 to 8 days, since the macula statica and crista ampullaris appeared in 6-7-day-old and in 7-8-day-old chick enbryos, respectively. In 12-day-old chick embryos, vestibular ganglion cells were arranged regularly in the direction proceeding from cells present in the ganglion.