Effect of tributyltin on the development of ovary in female cuvier (Sebastiscus marmoratus).

Organotin compounds, such as tributyltin (TBT) used as an antifouling biocide, can induce masculinization in female mollusks. However, few studies addressing the effect of TBT in fish have been reported. This study was conducted to investigate effects of TBT at environmental levels (1, 10, 100ng/L) on the development of ovary in female cuvier. TBT exposure elevated testosterone levels, increased the ratio of testosterone to 17beta-estradiol and decreased 17beta-estradiol levels in ovaries after 50 days compared to the control. Three stages of follicles (primary growth stage, yolk vesicle stage, vitellogenic stage) were observed in the ovaries of cuvier at the control and 1ng/L TBT group. The ovaries at the 10ng/L TBT group were characterized by the lack of vitellogenic stage follicles and instead had higher proportions of primary growth stage follicles. 100ng/L TBT resulted in follicles that were entirely at the earliest (primary growth stage) stages of development. There was a significant increase in apoptotic ovarian follicular cells judged by TUNEL-positive cell at the 10ng/L TBT group. The TUNEL-positive follicles were observed at the 100ng/L TBT group. The result in the present study showed that TBT at environmentally realistic concentrations can inhibit the ovarian development in fish. Besides the changes of sex hormone induced by TBT, apoptosis appears to be one mechanism affecting ovarian development.