Histological alterations in the structure of the testis in tench (Tinca tinca) after exposure to 17 alpha-ethynylestradiol

Abstract

Environmental pollution with synthetic estrogens may pose a serious threat to reproduction of aquatic wildlife species. The current study describes the effects of 17α-ethynylestradiol (EE2) on the structure of the testis in tench (Tinca tinca). Adult male tench were exposed to sublethal doses of EE2 (50, 100, and 500 μg/Kg t.w.) under semistatic conditions for a period of 30 days. The condition factor (CF), testicular somatic index (TSI), and histology (including a morphometric analysis) of the testis were examined. No consistent differences were observed in the CF of EE2-exposed tench when compared with nonexposed fish. A significant decrease in TSI could only be observed at a 50 μg/Kg t.w. EE2 dose (p < 0.05) when compared with the control group. The histopathology of the testis was associated with loss of normal tubular structure with increased doses of exposure, decrease of tubule number, degeneration in Sertoli and Leydig cells, increase in necrotic testicular cells including formation of syncytia structures and, finally, a high incidence of fish with early primary oocytes at 100 and 500 μg/Kg t.w. EE2. These results indicate that long-term exposure to EE2 may produce clear negative effects on testicular structure in tench.