|
(T/EH069) Is there a period in zebrafish development particularly sensitive to estrogen exposure? Maack, Gerd1, Segner, Helmut1, 1 ABSTRACT- To explore, if there exists a period in zebrafish sexual development, that is responsive on organisational effects of estrogens (sensitive window), we exposed zebrafish during different life stages to 10 ng/L Ethynylestradiol (EES) [2-14 days post fertilisation (dpf), 14 -41 dpf; 42- 71dpf; 72- 99 dpf]. The synthetic estrogen 17a -Ethynylestradiol has been detected in sewage effluents at levels up to 10 ng/L. Endpoints measured were: onset of spawning, reduced number of fertilised eggs per female per day and fertilisation rate. Exposure during 41- 71 dpf caused a significant delay in the begin of spawning, number of eggs and fertilisation rate. Histological examination at different developmental stages disclosed effects on the gonadal level. The effect elicited by a 4-week-exposure appeared to be reversible as indicated from the recovery of the fertilisation rate and egg number. A second counting starting on day 210 dpf, no longer showed a difference to the control group, whereas a life-time exposure to 10 ng/L EES let to irreversible infertility. The results suggest that the period between 42-71 dpf is a phase in zebrafish development, which is particular sensitive to the estrogen exposure. In our strain this window well agrees with the period of morphological testis differentiation. Key words: zebrafish, Ethynylestradiol, life stages |
