Fig. 6.17 Effects of hormonal treatment on the postaxillary glands in male Hymenochirus curtipes. A-C. One male was injected s.c. with 25 microliters of a synthetic GnRH agonist (12.5 micrograms/ml in amphibian Ringers saline) at “time zero”. D-F. Another male was injected s.c. with 25 microliters of amphibians Ringers saline at “time zero”. The frogs were photographed at time zero (A and D), after 90 minutes (B and E) and after 210 minutes (C and F) from injection. The frog treated only with Ringers solution showed no change in the size or appearance of its breeding gland over the 210 minute period (D-F). In contrast, the frog treated with the GnRH solution showed an increase in size and blood perfusion of the breeding gland even after 90 minutes (Fig. B), and the effect was still evident after 210 minutes (Fig. C). The ruler scale to the right of each picture is 1 mm. Photos and data kindly provided by Eric O. Thomas.