Diverse Regulation but Conserved Function: SOX9 in Vertebrate Sex Determination.

Sex determination occurs early during embryogenesis among vertebrates. It involves the differentiation of the bipotential gonad to ovaries or testes by a fascinating diversity of molecular switches. In most mammals, the switch is (sex determining region Y); in other vertebrates it could be one of a variety of genes including or Downstream of the switch gene, upregulation is a central event in testes development, controlled by gonad-specific enhancers across the 2 Mb locus. is a 'hub' gene of gonadal development, regulated positively in males and negatively in females. Despite this diversity, SOX9 protein sequence and function among vertebrates remains highly conserved. This article explores the cellular, morphological, and genetic mechanisms initiated by for male gonad differentiation.