Suzuki Aya, Nakamoto Masatoshi, Kato Yuko, Shibata Naoki
Department of Environmental System Science, Graduate School of Science and Technology, Shinshu University, Matsumoto, Japan.
Zoolog Sci. 2005 Jul;22(7):791-6. doi: 10.2108/zsj.22.791.
Sex reversal of XY male to functional females was induced by estrogen treatment during the embryonic period in the medaka Oryzias latipes. The present study aimed to examine whether exogenous estrogen (estradiol-17beta; E(2)) affects early sex differentiation, paying particular attention to DMY expression and proliferation activity of germ cells in estrogen treated XY individuals. Our results showed that germ cell number was not affected by E(2) treatment at hatching, and that DMY expression was not suppressed under conditions of sex reversal. Therefore, male differentiation of germ cells, which is triggered by the expression of DMY in the supporting cell lineage, proceeds even in E(2) treated XY individuals until hatching, and early sex differentiation is not altered by estrogen. However, sex reversal occurred after hatching probably because of estrogen remaining in the yolk. Interestingly, DMY expression was also detected in the large follicle layer of E(2 )treated XY ovary. These results suggested that DMY regulates male determination in early embryonic stage but does not suppress female follicle development.
在青鳉（Oryzias latipes）胚胎期，通过雌激素处理可诱导XY雄性向功能性雌性的性逆转。本研究旨在探讨外源性雌激素（17β-雌二醇；E₂）是否影响早期性别分化，特别关注经雌激素处理的XY个体中DMY的表达以及生殖细胞的增殖活性。我们的结果表明，孵化时生殖细胞数量不受E₂处理的影响，并且在性逆转条件下DMY表达未被抑制。因此，由支持细胞系中DMY的表达引发的生殖细胞雄性分化，在经E₂处理的XY个体中甚至持续到孵化，早期性别分化不受雌激素影响。然而，孵化后发生性逆转可能是因为卵黄中残留有雌激素。有趣的是，在经E₂处理的XY卵巢的大卵泡层中也检测到了DMY表达。这些结果表明，DMY在胚胎早期调节雄性决定，但不抑制雌性卵泡发育。
