title: Just how conserved is vertebrate sex determination?
abstract: BACKGROUND
  Sex determination in vertebrate embryos has long been equated with gonadal differentiation into testes or ovaries. This view has been challenged over the years by reports of somatic sexual dimorphisms pre-dating gonadal sex differentiation. The recent finding that sex determination in birds is likely to be partly cell autonomous has again called for a broader definition of sex determination. Inherent sexual differentiation in each and every cell may apply widely among vertebrates, and may involve more than one "master sex gene" on a sex chromosome. At the gonadal level, key genes required for proper sexual differentiation are conserved among vertebrates, but their relative positions in the ovarian and testicular cascades differ.
  
  
  RESULTS
  We illustrate these differences by comparing key sex genes in fishes versus birds and mammals, with emphasis on DM domain genes and the SOX9-AMH pathway in the testis and the FOXL2-Aromatase pathway in the ovary. Such comparisons facilitate the identification of ancient versus derived genes involved in gonadal sex determination.
  
  
  CONCLUSIONS
  The data indicate that vertebrate sex-determining cascades are not as conserved as once thought.
authors: Murdoch Childrens Research Institute, Royal Childrens Hospital, Parkville, Australia.
authors: Andrew
authors: A
authors: Cutting
authors: Justin
authors: J
authors: Chue
authors: Craig A
authors: CA
authors: Smith
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone / Q000235:genetics; D001141:Aromatase / Q000235:genetics; D001717:Birds / Q000196:embryology / Q000235:genetics; D019143:Evolution, Molecular; D005260:Female; D005399:Fishes / Q000196:embryology / Q000235:genetics; D051858:Forkhead Transcription Factors / Q000235:genetics; D006066:Gonads / Q000196:embryology / Q000378:metabolism; D008297:Male; D008322:Mammals / Q000196:embryology / Q000235:genetics; D055758:SOX9 Transcription Factor / Q000235:genetics; D019849:Sex Determination Processes / Q000235:genetics*; D012733:Sex Differentiation / Q000235:genetics; D014714:Vertebrates / Q000196:embryology* / Q000235:genetics*
chemical_list: D051858:Forkhead Transcription Factors; D055758:SOX9 Transcription Factor; D054304:Anti-Mullerian Hormone; D001141:Aromatase