In vivo sex differentiation of congeneic germinal cell aplastic gonads

Gonads of mice carrying a genetic mutation (SI/Sld), which results in failure of germinal ridges to become populated by the primordial germ cell line, continue to differentiate according to the genetic sex of the animal. The gonads from fetuses of 11, 12, 13, and 14 days' gestation were examined histochemically and histologically for the presence of germ cells and sex cord formation. In both normal and mutant fetuses, sex differentiation was found to progress according to the genetic sex. Testes from mutant adult male mice display well-developed seminiferous tubules populated by Sertoli cells only. Germinal cell aplastic ovaries have the appearance of streak gonads in that stromal tissue alone is present. These results affirm the concept that gonadal sex differentiation is an inherent function of the somatic gonadal elements, is not dependent upon the presence of the germ cell line, and may further help in explaining the etiology of some cases of germinal cell aplastic gonads.