多年來，培育鳥的人知道,，偶爾會自然地出現(xiàn)一種“半邊鳥”,。這些外觀奇特的鳥（亦稱為“雌雄嵌合體”）在羽毛、大小和其他特征上會極不對稱,，因?yàn)樯眢w的一邊像雄性,，而另一邊則像雌性,。有關(guān)性別確定的哺乳動物模型（按照該模型,，一個胚胎在性別上是中性的,，直到一個基因開關(guān)使產(chǎn)生性激素的性腺的發(fā)育啟動）過去一般被假設(shè)適用于所有脊椎動物?，F(xiàn)在,，對三個“半邊雞”所做的一項(xiàng)研究表明,，至少對鳥類來說，性別確定并不僅僅依賴于性腺,，而是整個身體中所有細(xì)胞的一個功能,。“半邊種”被發(fā)現(xiàn)是真正的雌雄嵌合體,，在它們當(dāng)中，各個細(xì)胞對性激素的同一混合物有不同反應(yīng),。這項(xiàng)工作提出了關(guān)于性別確定和性發(fā)育之性質(zhì)的普遍性問題,，這些問題此前似乎或多或少都已經(jīng)解決了。(生物谷Bioon.com)
延伸閱讀
人?；旌吓咛ィ函偪竦脑囼?yàn),？
2010年干細(xì)胞技術(shù)與應(yīng)用講座
生物谷推薦原文出處：
Nature vol.464 (7286), (11 Mar 2010) doi:10.1038/nature08852
Somatic sex identity is cell autonomous in the chicken
D. Zhao1,5, D. McBride1,5, S. Nandi1, H. A. McQueen3, M. J. McGrew1, P. M. Hocking2, P. D. Lewis4, H. M. Sang1 & M. Clinton1
1 Division of Developmental Biology and,
2 Division of Genetics and Genomics, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9PS, UK
3 Institute of Cell Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JR, UK
4 Animal and Poultry Science Department, University of KwaZulu-Natal, Pietermaritzburg, South Africa
5 These authors contributed equally to this work.
In the mammalian model of sex determination, embryos are considered to be sexually indifferent until the transient action of a sex-determining gene initiates gonadal differentiation. Although this model is thought to apply to all vertebrates, this has yet to be established. Here we have examined three lateral gynandromorph chickens (a rare, naturally occurring phenomenon in which one side of the animal appears male and the other female) to investigate the sex-determining mechanism in birds. These studies demonstrated that gynandromorph birds are genuine male:female chimaeras, and indicated that male and female avian somatic cells may have an inherent sex identity. To test this hypothesis, we transplanted presumptive mesoderm between embryos of reciprocal sexes to generate embryos containing male:female chimaeric gonads. In contrast to the outcome for mammalian mixed-sex chimaeras, in chicken mixed-sex chimaeras the donor cells were excluded from the functional structures of the host gonad. In an example where female tissue was transplanted into a male host, donor cells contributing to the developing testis retained a female identity and expressed a marker of female function. Our study demonstrates that avian somatic cells possess an inherent sex identity and that, in birds, sexual differentiation is substantively cell autonomous.
