Reproductive Cvcle-related Changes in GnRH Immunoreactivitv in the Brains of Three Congeneric Species of Frog.

3종의 개구리 뇌에서 생식주기에 따른 GnRH 면역반응성의 변화

Seasonal variations of GnRH were investigated by immunohlstochemicsl technique in three species of frog, Rona niEromaculutu, R. dvbowskii 8nd R. mgosa with different ovulation period in order to examine the relationship between GnRH expression and reproductive function. In all three species of frog, the intensity of GnRH immunoreactivitv and the number of GnRH neurons in the brawn were relatively high in frogs at the pre-ovulation period and markedly increased at the ovulation period. Those were then decreased after ovulation and further lowered during early hibernation period. These results indicate that GnRH experssion is closely related to specific phases of annual reproductive cycle in frog.