Genital Tubercles, Urethrogenesis and the Genital Organizer.
Genital Tubercles, Urethrogenesis and the Genital Organizer.
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生殖器结节、尿道发生和生殖器组织者。
DOI：
10.1016/j.juro.2016.07.044
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Baker,LindaA
中科院分区：
文献类型：
--
作者：
Baker,LindaA
DURING the formation of an embryo, how does a mass of cells morph into an organ? What an amazing, mysterious and complex process. Embryologists know that such embryonic body planning events follow common themes. In general, early organogenesis requires 3 phases, including 1) that a primitive cell mass called the anlagen be present and in the proper location relative to the rest of the body (the anlagen phase), 2) that the anlagen be acted upon by morphogens (factors that induce shape change), which are secreted from properly positioned cellular organizing centers to increase the overall anlagen cell mass and pattern the formation of key anatomical structures of the basic organ (the patterned organ phase), and 3) if applicable, that the basic patterned organ be acted upon by sexually divergent hormones to yield sexually dimorphic organs at birth (the sexually dimorphic organ phase).Focusing on the formative events of the penis and the clitoris, the primitive anlagen (the paired genital swellings) are perched close to the anterior cloaca and the developing bony pelvis. The genital swellings fuse into the genital tubercle, which is composed of a mesodermal core covered by an ectodermal surface. As a developing body appendage, the genital tubercle shares features with limb and digit embryonic development, including the aim to pattern differentially on 3 spatial planes, namely proximodistal, anteroposterior and mediolateral. 1 To achieve this differential patterning, on the ventral surface of the genital tubercle the endodermal urethral plate grows distally out from the cloaca and functions as the critical genital tubercle organizing center by secreting potent morphogens such as sonic hedgehog (Shh). 1 In this issue of The Journal Armfield et al (page 1295) used a sophisticated, comprehensive and relatively unbiased approach to identify abundantly expressed genes in the early embryonic mouse urethral plate genital organizer. 2 At day 12 of embryonic life and prior to sexual differentiation of the genital tubercle the urethral plate produces the morphogen Shh. After using a cell sorting technique that selects out the urethral plate cells producing
