The distribution and developmental changes of hatching gland cells during phylogenesis have a subject of great interest to embryologists. Our knowledge on the hatching gland cells in the Class Osteichthyes is very limited at present, and our investigations on them having been less progressed.
Here the present authors have undertaken, with the above view in mind, a comparative study on the development of the hatching gland cells in embryos of two species of fresh-water teleosts, Macropodus opercularis and Betta splendens. There may be a expectancy of this study contributes something to the morphological aspects of development.
In embryos just before hatching of the two species, the distribution of hatching gland cells was observed. In embryos of Macropodus opercularis, the number of the hatching gland cells approximates 370 in total. The cells are found in the epithelium covering the surface of the upper region of the head. In embryos of Betta splendens, the hatching gland cells numbering about 180 in total. They appear in the epithelium covering the surface of the highest region of the head.