Mammalian sex determination

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  although the genetic basis of mammalian sex determination and differentiation has advanced considerably in recent years, a majority of 46,xy gonadal dysgenesis patients still cannot be provided with an accurate diagnosis. Some of these unexplained dsd cases may be due to mutations in novel dsd genes or genomic rearrangements affecting.   sry, the mammalian y-chromosomal testis-determining gene, induces male sex determination. Recent studies in mice reveal that the major role of sry is to achieve sufficient expression of the related gene sox9, in order to induce sertoli cell differentiation, which in turn drives testis formation. Human sex determined by sex chromosomes 46xx is normal female, 46xy is normal male. 45xo female, turners syndrome short stature, webbing of neck, underdeveloped secondary sexual characteristics, sterile due to degeneration of gametes and ovaries after birth turners syndrome fully expressed in females lacking short arm of one x. It is still bi-potential because somatic sex determination is yet to occur. If the somatic cells in the gonad are xx, an ovary tends to form. Although the sex-specific behavior of germ cells during fetal life has been recognized for many decades, it is. Our knowledge of mammalian sex determination is based on two main areas of study. First, the characterization of the biological events that determine the sexual development of the individual, including patterns of gene expression, and second, the study of genetic mutations in humans and mice that lead to abnormal sexual phenotypes. A regulatory cascade hypothesis for mammalian sex determination, proposing thatsryrepresses a negative regulator of male development, was recently supported by observation of mice that expressed adax1transgene and developed as xy sex-reversed females.

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