Immunofluorescence studies on gonadotropin releasing hormone (GRH) in the fore-brain and the neurohypophysis of the green frog, Rana esculenta L.

Using antibodies against mammalian LH-RH, the double antibody-immunofluorecence technique has been applied to serial cross sections of the brains of adult Rana esculenta. Immunoreactive material was found in perikarya of an unpaired nucleus in front of the preoptic recess. The axons of these perikarya also contain fluorescing material. They form a single bundle which passes under the preoptic recess, than splits into two tracts, one on either side of the optic chiasm. The two tracts reunite just before entering the median eminence. The axons end near the capillaries in the outer zone of the median eminence. The possibility of two separate centres for the stimulation of gonadotropic activity in the brains of anurans is discussed.