Commercially Available Vitamin A Palmitate is Toxic and Teratogenic to the Tadpoles of Microhyla nilphamariensis (Anura: Microhylidae)

Aim/Background: The present study, examined the impact of excess Vitamin A on feeding and pre-metamorphic tadpoles of Microhyla nilphamariensis to analyse its dose-dependent and stage-specific lethal and teratogenic effects. Materials and Methods: Feeding and pre-metamorphic stage tadpoles were subjected to varying concentrations of commercially available Vitamin A palmitate for different time intervals. The control and treated tadpoles were fixed 5, 10-and 15-Days Post Treatment (dpt) in neutral buffered formalin for morphological analyses, morphometry and histology. Results: In both feeding and pre-metamorphic stages, mortality was high when exposed to higher concentrations and longer duration (48-96 hr). When exposed for 24 hr, the treated tadpoles showed significant differences in morphometry, and abnormalities in the eye and intestine of the feeding stages and eye and kidneys of pre-metamorphic stages. Significantly, most of the treated tadpoles died before attaining metamorphosis and those that survived had a delayed metamorphosis with abnormalities. Conclusion: Vitamin A is lethal to the tadpoles of Microhyla nilphamariensis at high concentrations and at lower concentrations it affects the thyroid hormone function and causes abnormalities of various kinds.