Abstract
In embryonic development, myelinization on the perikarya of the eighth cranial nerve ganglion cells is first observed in about-17-day chick embryos. It progresses, gradually increasing both thickness and compactness of each sheath as well as number 'of myelinated neurons. The well-developed myelin sheath, however, does not occur until about 3 days after hatching. A few myelinated fibers are contained in the eighth nerve of 13-day chick embryos already.
