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Determination of Sex


It is important to know that estrogens do not appear to be required for differentiation or development of the female reproductive tract during fetal development.


Sertolli cells of the testes synthesize Mullerian Inhibiting Hormone or MIH also known as Anti Mullerian Hormone or AMH, which causes regression and disappearance of the Mullerian(paramesonephric) duct structures. The Leydig cells of the testes respond to human choriogonadotropin produced by the placenta by synthesizing testosterone. This testosterone stimulates the structures of the Wulffian ducts to develop into the male reproductive tract.

Some components of the male genitalia including the urethra, prostate, penis and scrotum, convert testosterone to dihydrotestosterone or DHT via the enzyme 5 alpha reductase and respond preferentially to dihydrotestosterone rather than to testosterone. Since Dihydrotestosterone is considerably more potent than testosterone, a defect in the 5 alpha reductase enzyme results in incomplete development of these structures during fetal development.

The epididymis of the fetal male is not dependent on conversion of testosterone to dihydrotestosterone although the epididymis of the adult male is dependent on the conversion of testosterone to dihydrotestosterone.