XY females phenotypically develop into females because the presence of the Sry gene alone is not sufficient to fully determine male gonad development. In addition to Sry, other genetic and hormonal factors are required for the development of testes and the subsequent production of male sex hormones, such as testosterone.
Even though 15% of XY females have the Sry gene, they may lack other genetic factors or hormonal influences necessary for testis development and male phenotypic characteristics. Furthermore, the presence of ovary-forming genes in these individuals may also contribute to the development of female phenotypes.
Thus, the development of male or female gonads and phenotypes is a complex process that involves the interaction of multiple genes and hormones. The absence of certain factors or the presence of conflicting factors can lead to the development of female phenotypes despite having the Sry gene.
During primary sex determination in mammals, the presence of Sry gene on the Y-chromosome is the major factor in determining if male or female gonads will develop. Expression of Sry protein activates the Sox9 gene, which triggers the expression of testis-forming genes and blocks the expression of ovary-forming genes. XY females are genotypically male but phenotypically female. If 15% of XY females have the Sry gene, why do they phenotypically develop into females?
1 answer
1 answer