Stage-specific malformations and phenotypic changes induced in embryos of amphibian (Xenopus tropicalis) by triphenyltin.

Tributyltin (TBT) and triphenyltin (TPT) can induce unique malformations in embryos of amphibian (Xenopus tropicalis). We further exposed X. tropicalis embryos to TPT during different stages. Severe malformations were observed in the embryos after exposure to 5-10 μg Sn/L TPT during S32-40 and S40-46. Comparatively, the embryos showed slight or moderate malformations after exposure during S10-25, S25-32 or S46-47. The most characteristic malformations were narrow or no fins, followed by enlarged proctodaeums and skin hypopigmentation. The developed fins were still affected after TPT exposure, but the inhibited fins could not recover even after the removal of TPT exposure. In TPT treatment groups, the proctodaeums of embryos externally expanded, and the pigment cells of embryos were poor, small and dot like. Our results suggested that TPT-induced teratogenicity was highly stage-specific. The sensitive window of fin defects indicated that TPT affected the formation rather than induction or expansion of fins.