[Response of the seminal vesicles of Gobius niger L. to castration, followed or without treatment with free or conjugated testosterone].

When approaching seasonal sexual maturity, precocious gonadectomy performed at the end of April induced seminal vesicle regression, but more tardive surgery performed 1 month later did not induce any regression. This unexpected result was interpreted as a change in the endocrine determinism. Among the precocious gonadectomized Fish, testosterone implants inhibited seminal vesicle regression but implants of sulfate-conjugated testosterone did not.