The neural crest and the acoustic ganglion

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Abstract
There is no agreement about the origin of the acoustic ganglion. Some investigators maintain that it originates in the neural crest, and others that it arises from the otic placode. It was thought that mutant genes might help in resolving the doubt. The gene piebald-lethal (s1) affecting pigmentation in the mouse was selected for this purpose. There was strong evidence that the piebald locus influenced the development of the neural crest before its differentiation into melanoblasts and ganglionic primordia. Histological examination revealed striking abnormalities in the inner ear of all piebald-lethal mice. The neural epithelium was invariably affected. In view of the known action of the piebald locus on the neural crest and the intimate developmental relationship between the acoustic ganglion and the neural epithelium, the most plausible explanation of these abnormalities is that the neural crest contributes to the formation of the acoustic ganglion in the mouse. This conclusion is supported by studies on two other mutants (white and pallid) in which defects of pigmentation and the inner ear occur together. The presence of similar abnormalities, either observed or deduced from deafness, in the inner ear of white cats and piebald dogs suggests that the acoustic ganglion in these animals has a similar origin.