Clinical relevance of fetal gonadal structure and function.

: The foregoing discussion is consistent with the following conclusions: First structural differentiation of the gonads, consonant with chromosomal sex of human fetuses, requires complex interactions of primordial germ cells with coelomic and mesonephric epithelial cells and mesenchymal cells in the genital ridge. The mediators of these interactions remain to be defined. Second, the male fetal gonads secrete substances that direct differentiation of gonaducts and external genitalia along lines consonant with the sex chromosomal constitution. Third, when fetal gonads fail to secrete these substances or target tissues fail to respond, gonaducts or genitalia or both are either phenotypically female or ambiguous, regardless of fetal sex chromosomal constitution. Fourth, although the role of pituitary hormones in gonadal differentiation remains uncertain, the fetal pituitary appears to be required for maintenance of structural and functional integrity of differentiated fetal gonads.