Abstract: Xenopus tropicalis embryos were exposed to 200 ng·L^-1 tributyltin chloride (TBTCl) during different periods in the experiement of three days. The percent of survival embryos decreased by 10% in the 3rd, 20% in 3 d treatment groups, respectively. The whole body length reduced by 30% in the 2nd day, 20% in the 3rd day and 39% in 3 d treatment groups, respectively. More than 90% embryos showed malformations in treatment groups. The main characteristic malformations were abnormal eyes, enlarged proctodaeum, narrow fins or absence of fins, bent tails, etc. Compared with the control, the eyes were smaller in the 2nd day and bigger in the 3rd day treatment groups, respectively. The dorsal fins were a little narrower in the 1st day treatment group, both dorsal and ventral fins were much narrower with tail-tip residue or gap near the proctodaeum in the 2nd day treatment group, and the fins were slightly narrower in the 3rd day treatment group, respectively. The results suggest that the malformations in the eyes and fins were more sensitive to different exposure periods.

Key words: tributyltin (TBT), Xenopus tropicalis, embryos, teratogenesis