Vestibular Ganglion as a Model System of Vital-neural Centre During Embryonic Development

Abstract

Chick embryos at different stages of development till hatching as well as vestibular ganglia of the adult were fixed in formol-saline. Serial sections were stained by Cresyl Fast Violet to analyse the results in the vestibular ganglion. Neurones were categorised and counted. The appearance of a few light cells on Embryonic day 6 (E6) might indirectly indicate the beginning of an early establishment of functional connections in the vestibular ganglion in contrast to most other ganglia studied. The fluctuation in the number of cells during embryonic development may be considered as a normal process for the purpose of rearrangement for better organisation in order to perform an efficient function. Volume of the vestibular ganglion is the greatest on Embryonic-day 18 (E18) during the whole ontogeny even though its rostra-caudal length is greatest in the adult. This is in contrast to that observed in several other ganglia where the ganglionic volume is the greatest in the adult situation. The reduction or loss of ganglionic neurones in the adult in comparison to that observed on the day. of hatching might indicate a functional reduction as a result of ageing process. The appearance of an increased number of tiny cells in the adult in comparison to that observed on the day of hatching is different and peculiar from that observed in other ganglia studied. These new cells are probably derived from active mitoses of reserved neuroblasts. This possibly provides an attempt to replace the inactive/or dead cells during ageing process.