Estradiol-17? content in developing eggs and induced sex reversal of the medaka (Oryzias latipes)
✍ Scribed by Iwamatsu, Takashi ;Kobayashi, Hirokuni ;Hamaguchi, Satoshi ;Sagegami, Reiko ;Shuo, Takuya
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 113 KB
- Volume
- 303A
- Category
- Article
- ISSN
- 1548-8969
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
To clarify the effect of exogenous estradiol‐17β (E~2~) on sex differentiation, the E~2~ content of developing eggs of Oryzias latipes was measured by radioimmunoassay. Endogenous E~2~ was present in lower concentrations in ovulated, mature eggs in the ovarian cavity than in intrafollicular oocytes. The E~2~ content of eggs precipitously declined to a minimum level by 2 days post‐fertilization. The E~2~ content of eggs was affected by 24 hr of incubation in medium containing exogenous E~2~ at concentrations above 10 ng/ml. Short (24 hr) exposure of fertilized eggs in the early developmental stage to exogenous E~2~ at concentrations of 10 ng/ml induced sex reversal of some genotypic males to functional females. However, endogenous E~2~ levels in fertilized eggs might not influence sexual differentiation in embryogenesis. The present results suggest the possibility that concentrations of exogenous E~2~ higher than that of endogenous E~2~ triggers a priming step in the cascade of sex differentiation toward the female, and this effect is maintained. J. Exp. Zool. 303A:161–167, 2005. © 2005 Wiley‐Liss, Inc.