Seasonal variations in the pharyngeal and pronephric thyroid tissues of the fresh water teleost Puntius sophore (Ham).

An attempt has been made to study pharyngeal and pronephric thyroid follicles and contribute seasonal changes in them in a fresh water teleost, Puntius sophore. Their activity has been assessed histologically by the study of size of thyroid follicles, the shape and cell height of epithelial cells and the nature of their colloid. These follicles exhibit notable seasonal changes and record two periods of activity, one in summer months from May to August and the other in November.