Preliminary study of gonadotropin-releasing analogue (GnRH-A) initiated gonadal development of amphioxus

Amphioxus in the seasonally regressed phase of gonadat development were used in this study. Each sample animal was injected with 40 nanogram of synthetic gonadotropin-releasing hormone analogue (GnRH-A) in distilled water every other day for up to 16 days; control animals received similar volumes of distilled wnter only. Both hormone-treated samples and control animals were examined under microscope every eight days and every twelve days. Then all the animals were killed on the 16th day. Gonads earlier development and a more advanced degree of gametogenesis are in the hormone-treated group than in the control group. Thus, GnRH-A can initiate and accelerate the gonadal development in gonadally regressed amphioxus. GnRH-A in some form may be important in regulating the gonadal development in amphioxus as well as in vertebrates.