Response of immature gonads of Ceratophrys ornata to FSH

Abstract

Follicle-stimulating hormone (FSH) injected into recently metamorphosed toad Ceratophrys ornata, a differentiated race which differentiates its gonads shortly before metamorphosis, brings about in the male gonad the transformation of the solid testicular cords into a spongelike network of testicular ampullae containing only one type of germinal cell, the spermatogonia, surrounded by typical follicular cells. In the female gonad, there is no ampullae formation, but a remarkable increase in germinal cell population. This different response shows that the female gonad is more sensitive to the proliferative stimulation of FSH than the male gonad. In recently metamorphosed toads of the species Ceratophrys ornata, in contrast to another differentiated race, Pleurodema cinerea, which differentiates its gonads long before metamorphosis, FSH treatment fails to produce a complete spermatogenesis. We conclude that the time of differentiation of the male gonad is the important factor in the response to FSH, not the sex race.