Murdoch Childrens Research Institute, Royal Childrens Hospital, Parkville, Australia.
Dev Dyn. 2013 Apr;242(4):380-7. doi: 10.1002/dvdy.23944. Epub 2013 Mar 6.
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.
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.
The data indicate that vertebrate sex-determining cascades are not as conserved as once thought.
长期以来，脊椎动物胚胎的性别决定一直被等同于性腺分化为睾丸或卵巢。多年来，有报道称存在性器官分化之前的躯体性别二态性，这一观点受到了挑战。最近发现鸟类的性别决定可能部分是细胞自主的，这再次呼吁对性别决定进行更广泛的定义。每个细胞中固有的性别分化可能在脊椎动物中广泛存在，并且可能涉及性染色体上的不止一个“主性别基因”。在性腺水平上，鱼类、鸟类和哺乳动物中所需的适当性别分化的关键基因是保守的，但它们在卵巢和睾丸级联中的相对位置不同。
我们通过比较鱼类与鸟类和哺乳动物中的关键性别基因来举例说明这些差异，重点是睾丸中的 DM 结构域基因和 SOX9-AMH 途径，以及卵巢中的 FOXL2-芳香酶途径。这种比较有助于确定参与性腺性别决定的古老基因和衍生基因。
这些数据表明，脊椎动物性别决定级联并不像以前认为的那样保守。
