Development of the Tissue Architecture in the Gonads of the Medaka Oryzias latipes(Developmental Biology)

概要

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Development of the gonads in the medaka was studied by electron microscopy from embryonic stages to the completion of the formation of male and female gonads to presume the role of somatic cells in germ cell development. Somatic cell constituents of the gonads were derived only from the lateral plate mesoderm. They differentiated into two types of cells, distinguished by the relation to germ cells and the presence of the basal lamina, around the time of hatching. One cell type differentiated into the Sertoli cells and efferent duct of the testis and into granulosa cells and epithelia lining the ovarian cavity in the ovary. The other cell type, after differentiation, formed the remaining part of the gonad, including the steroid producing cells. The timing of the first appearance of steroid producing cells was similar in both sexes and occurred following gonadal sex differentiation. Thus, these findings do not favor the hypothesis that steroid hormones are involved in the induction ofgonadal sex differentiation in the medaka. The compartmentation of spermatogonia in the testis was accomplished rather early; this compartmentation may be related to the delayed mitosis and meiosis of spermatogonia. The number of steroid producing cells in the testis markedly increased immediately prior to meiosis, suggesting the involvement of steroid hormones, probably androgens, in the induction of meiosis in males.
1985-10-15