author(s)
Padmanabha Chakrabarti, Shruti Ghosh

abstract
The present investigation dealt with the cytological status of thyroid follicles and correlated them with the changes of testicular activities in male Tenualosa ilisha (Hamilton). On the basis of tinctorial properties, each follicle possessed a central lumen either fully or partially filled up with the agranular eosinophilic colloidal materials and the lumen was encircled by a single layer of epithelial cells. The secretory activity of the follicles fluctuated in harmony with the testicular cells during growth, maturation and spawning phases in T. ilisha. The low active condition of the thyroid follicles during the growth phase was well coincidence with the increase of spermatogonial and spermatocyte cells. The most active condition of the thyroid follicles were noted during the end of maturation and spawning phases correlated with the highest frequency percentage of spermatids and spermatozoa. It was concluded that the cytological changes in the thyroid follicles and testicular activities correlate well during growth, maturation and spawning phases in male T. ilisha.