Cool Jonah, Capel Blanche
Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Semin Reprod Med. 2009 Jan;27(1):5-13. doi: 10.1055/s-0028-1108005. Epub 2009 Feb 5.
Induction and patterning of the testis occurs over a brief window of time. Before male-specific morphogenesis, the gonad primordium is bipotential and capable of developing into either an ovary or testis. However, expression of the transcription factor SRY initiates male development and induces patterning, proliferation, and epithelialization specific to the testis. Male sex determination begins with commitment of Sertoli cells via autonomous and nonautonomous mechanisms. These mechanisms have recently been shown to both promote the male fate and simultaneously repress ovarian development. A second critical event in the development of the testis is the epithelialization of testis cords. After their specification, Sertoli cells epithelialize and surround the male germ line to form large looping structures bound by extracellular matrix. Cells excluded from cord structures are called interstitial cells and comprise several different cell types, including steroidogenic cells, endothelial cells, and a smooth muscle cell that directly surround the cords. Numerous male-specific signaling pathways influence testis cord morphogenesis and specification of distinct cell types, although a coherent progression of events is unclear. In this article we focus on signals in the male gonad that first are responsible for the specification of Sertoli cells, and second for the specification and patterning of interstitial cells.
睾丸的诱导和模式形成发生在一个短暂的时间段内。在雄性特异性形态发生之前，性腺原基具有双向潜能，能够发育成卵巢或睾丸。然而，转录因子SRY的表达启动雄性发育，并诱导睾丸特有的模式形成、增殖和上皮化。雄性性别决定始于支持细胞通过自主和非自主机制的定向分化。最近的研究表明，这些机制既能促进雄性命运的发展，又能同时抑制卵巢发育。睾丸发育中的第二个关键事件是睾丸索的上皮化。在其特化之后，支持细胞上皮化并围绕雄性生殖系，形成由细胞外基质包围的大的环状结构。被排除在索状结构之外的细胞称为间质细胞，包括几种不同的细胞类型，如类固醇生成细胞、内皮细胞和直接围绕索状结构的平滑肌细胞。许多雄性特异性信号通路影响睾丸索的形态发生和不同细胞类型的特化，尽管事件的连贯进展尚不清楚。在本文中，我们重点关注雄性性腺中的信号，这些信号首先负责支持细胞的特化，其次负责间质细胞的特化和模式形成。
