Owing to the lack of a complete series of embryos, T have been unable to trace the earlier stages of the development of the ear. In all the Amphibia, so far as studied, unless we except the species of Axolotl figured by Houssay, and he was doubtless in error, the ear arises as a differentiation of the inner of the two layers into which the ectoderm is early divided. This inner sensory layer thickens on each side of the head so as to form a small sensory tract, the anlage of the ear, closely analogous, if not homologous, in formation to the lateral line sense organs. An ingrowth or in pushing of the thickened ectoderm results in the formation of a pit. The outer layer of indifferent ectoderm takes no share in the formation of the auditory vesicle, but it is slightly involuted into the opening of the pit. The pit deepens, its edges approach each other until the pit becomes a closed vesicle.
Proceedings of the Iowa Academy of Sciences
©1893 Iowa Academy of Science, Inc.
Norris, H. W.
"The Development of the Auditory Vesicle in Necturus,"
Proceedings of the Iowa Academy of Science, 1(Pt. 4), 105-107.
Available at: https://scholarworks.uni.edu/pias/vol1/iss4/34