Laboratory of Molecular Neuroscience, School of Biomedical Science and Medical Research Institute, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
Nat Commun. 2013;4:1372. doi: 10.1038/ncomms2372.
Sexual differentiation leads to structural and behavioural differences between males and females. Here we investigate the intrinsic sex identity of the brain by constructing chicken chimeras in which the brain primordium is switched between male and female identities before gonadal development. We find that the female chimeras with male brains display delayed sexual maturation and irregular oviposition cycles, although their behaviour, plasma concentrations of sex steroids and luteinizing hormone levels are normal. The male chimeras with female brains show phenotypes similar to typical cocks. In the perinatal period, oestrogen concentrations in the genetically male brain are higher than those in the genetically female brain. Our study demonstrates that male brain cells retain male sex identity and do not differentiate into female cells to drive the normal oestrous cycle, even when situated in the female hormonal milieu. This is clear evidence for a sex-specific feature that develops independent of gonadal steroids.
性分化导致雄性和雌性之间的结构和行为差异。在这里，我们通过构建鸡嵌合体来研究大脑的内在性别身份，在性腺发育之前，将脑原基在雄性和雌性身份之间切换。我们发现，具有雄性大脑的雌性嵌合体表现出性成熟延迟和不规则的产卵周期，尽管它们的行为、血浆中性类固醇和促黄体激素水平正常。具有雌性大脑的雄性嵌合体表现出类似于典型公鸡的表型。在围产期，遗传上为雄性的大脑中的雌激素浓度高于遗传上为雌性的大脑中的雌激素浓度。我们的研究表明，即使处于雌性激素环境中，雄性脑细胞也保留雄性性别身份，不会分化为雌性细胞来驱动正常的发情周期。这是一个明确的证据，表明存在一种独立于性腺类固醇发育的性别特异性特征。
