Morphological changes in the oral (Buccopharyngeal) membrane in urodelan embryos: Development of the mouth opening
Article first published online: 6 FEB 2005
Copyright © 1988 Wiley-Liss, Inc.
Journal of Morphology
Volume 195, Issue 1, pages 59–69, January 1988
How to Cite
Takahama, H., Sasaki, F. and Watanabe, K. (1988), Morphological changes in the oral (Buccopharyngeal) membrane in urodelan embryos: Development of the mouth opening. J. Morphol., 195: 59–69. doi: 10.1002/jmor.1051950106
- Issue published online: 6 FEB 2005
- Article first published online: 6 FEB 2005
The ultrastructure of the oral (buccopharyngeal) membrane in the embryo of the urodelan, Hynobius tokyoensis, was examined by transmission (TEM) and scanning electron microscopy (SEM). The oral membrane consists of the stomodeal ectoderm and foregut endoderm, and is three to five cell layers thick at stage 24. The oral membrane gradually thickens as development proceeds. The stomodeal collar, derived from the ectoderm, is folded inward along the foregut endoderm. Tooth germs are formed partly by cells of the stomodeal collar and partly by mesenchymal cells and calcification takes place before hatching. Secretory granules, which are markers of epithelial differentiation, appear in some cells of the foregut endoderm. Within the oral membrane, the cells of the stomodeal collar become the basal cells, and the endodermal cells of the foregut become the apical cells of the future oral epithelium. Gaps are formed by the epithelial differentiation of the endodermal cells of the foregut in the oral membrane. The gaps connect with each other, with the stomodeum, and with the foregut. As a result of these events, the mouth opens at stage 43, just after hatching.