Germ cell depletion does not alter the morphogenesis of the fetal testis or ovary in the red-eared slider turtle (Trachemys scripta)

In the red-eared slider turtle, Trachemys scripta, both prospective male and female gonads contain primitive cord structures at the time when the gonad first forms. Primordial germ cells arrive in the gonad and accumulate on the coelomic surface. If testis development is initiated, these cords develop further at the same time that germ cells migrate from the coelomic surface and become sequestered in the interior of the cords. In contrast, in-the developing ovary germ cells proliferate in a defined cortical domain, while the primitive cords regress and form flattened lacunae in the medulla. Because of their intimate association with these developmental processes, we investigated whether germ cells were required in turtles to establish the morphology of the fetal testis and ovary. We present evidence that normal morphological development of the fetal gonad occurs in both sexes in T. scripta after germ cell depletion, suggesting a conservation of developmental mechanisms across vertebrates.