Overview on sex determination and Sexual ambiguity

Alfred Jost (1974) showed that all mammalian embryos naturally resulted in female offspring. Therefore, to produce male offspring, some factors need to intervene in this natural process. The SRY gene differentiates the genital ridges to the testis. The testis secrets two essential hormones: anti-Mullerian factor inhibits the growth of the Mullerian system and testosterone initiates the growth of the Wolffian duct and converts the urogenital sinus to male external genitalia. Any error in this long and complicated process results in ambiguous genitalia which could be minor or major according the severity of the error. In 2005, the results of the errors were termed “Disorders of Sex Development (DSD)” which includes a vast range of ambiguities in human genital that are classified according to the etiology: I. Sex chromosomal aberrations II. Gonadal dysgenesis III. Enzyme defects (under or over expression) IV. Anatomical abnormalities We will discuss them more in the following issues of Genetics in the 3rd Millennium.