Effect of Vitamin A on Development of Thyroid Gland in Bufo melanostictus Stage 25 & Stage 30

Abstract

The effect of vitamin A on development and differentiation of thyroid gland with particular reference of Bufo melanostictus (schneider) tadpoles of stage 25 and 30 of this toad species. Tadpoles of stage 25 does not give any obvious indication of presence of thyroid gland at the expected site but stage 30 show well developed thyroid gland. Vitamin A treatment to the tadpoles of stage 25 & 30 reduction in the size of thyroid gland as well as decrease in the size of colloid in such cases. Tadpoles of discontinuous treated group shows quite normal thyroid similar to the untreated group in stage 30 but tadpoles of stage 25 group C do not metamorphose after fifteen days. Vitamin A has been found to affect differentiation of thyroid gland in the toad tadpoles and the effect is more severe on younger tadpoles as compared to the older ones.