Rahmoun Massilva, Perez Julie, Saunders Paul A, Boizet-Bonhoure Brigitte, Wilhelm Dagmar, Poulat Francis, Veyrunes Frédéric
Institut des Sciences de l'Evolution de Montpellier, Université Montpellier 2, CNRS, IRD, Montpellier, France.
Sex Dev. 2014;8(6):356-63. doi: 10.1159/000368664. Epub 2014 Oct 29.
The African pygmy mouse Mus minutoides is characterized by the presence of a high proportion of fertile XY females in natural populations. This species displays 2 morphologically different X chromosomes: the ancestral X and a shorter one designated as X*, feminizing the XY individuals. This strongly suggests that in the presence of an X chromosome, the male differentiation program is not activated despite a functional Y chromosome. In this study, we compared the histology of the adult ovaries of the 3 female genotypes (XX, XX* and XY) and investigated the expression of some of the main genes involved in male and female differentiation. We found that XY gonads display a typical ovarian structure without any testicular organization. Moreover, the ovarian somatic marker FOXL2 is detected in XY follicle cells and exhibits the same pattern as in XX and XX ovaries, whereas SOX9 and DMRT1 are absent at all stages of follicular differentiation. However, surprisingly, XY ovaries display a higher level of Sry transcripts compared to testes. Our findings confirm the complete sex reversal in XY individuals with no apparent sign of masculinization, providing an attractive model to unravel new gene interactions involved in the mammalian sex determination system.
非洲侏儒小鼠（Mus minutoides）的特点是在自然种群中有高比例可育的XY雌性个体。该物种有两种形态不同的X染色体：祖传X染色体和一条较短的被命名为X的染色体，它会使XY个体雌性化。这强烈表明，在存在X染色体的情况下，尽管Y染色体功能正常，但雄性分化程序并未被激活。在本研究中，我们比较了三种雌性基因型（XX、XX和XY）成年卵巢的组织学，并研究了一些参与雄性和雌性分化的主要基因的表达。我们发现，XY性腺呈现典型的卵巢结构，没有任何睾丸组织。此外，在XY卵泡细胞中检测到卵巢体细胞标记物FOXL2，其表达模式与XX和XX卵巢中的相同，而在卵泡分化的所有阶段都未检测到SOX9和DMRT1。然而，令人惊讶的是，与睾丸相比，XY卵巢中Sry转录本的水平更高。我们的研究结果证实了XY个体完全性逆转，且没有明显的雄性化迹象，为揭示哺乳动物性别决定系统中涉及的新基因相互作用提供了一个有吸引力的模型。
