Effects of castration and/or hypophysectomy on the seminal vesicles of the catfish, heteropneustes fossilis (Bloch)

The response of the seminal vesicles to hypophysectomy and/or castration during the prespawning and the spawning periods was studied. Forty days post‐hypophysectomy the seminal vesicles regress completely, whereas 40 days postcastration they show hyperactivity which is accentuated by 85 days post‐surgery. Further, catfish castrated in the prespawning period of 1966 not only show hyperactive seminal vesicles in that season but also exhibit hypersecretory seminal vesicles in the following breeding season, in spite of the absence of the testes. In the castrate catfish, hyperactivity in the seminal vesicles is accompanied by a significant increase in the number and activity of the granulated basophils in the pituitary and an increase in the nuclear diameter of the interrenal cortical cells. Two hypotheses are proposed to explain this paradoxical phenomenon.