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Comparative development study of the cloacal separation and formation of anal canal

泄殖腔分离与肛管形成的比较发育研究

基本信息

批准号：
16590137
负责人：
AKITA Keiichi
金额：
$ 2.18万
依托单位：
Tokyo Medical and Dental University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16590137/
关键词：
cloaca anorectal canal external anal sphincter programmed cell death genital tubercle pectinate line pelvis programmed cell death 櫛伏線尿直腸間隙マウス三次元立体構築

项目摘要

The anorectal canal has two origins ; the upper part is derived from endoderm and the lower part is derived from ectoderm. The process of ectodermal contribution to the canal is remains unclear. To understand the development of this area, serial sagittal sections of mouse embryos were made every 12 hrs from embryonic day 13.0 (E13.0) to E18.5. Three-dimensional reconstructions were obtained from these sections. At the disappearance of the cloacal membrane (E13.5), endodermal lining reached the site of disintegrated membrane. Thus the whole canal had endodermal origin. The dorsal end of the primary perineum was thicker than other ectodermal epithelium, and in this transitional region it changed from an acute to obtuse angle. After it straightened out and formed the canal, the secondary perineum appeared caudally. During these processes, the external sphincter appeared in the underlying mesenchyme of the thick ectoderm, and functioned as a drawstring to form the ectodermal anal canal.

肛门直肠管有两个来源：上半部分起源于内胚层，下半部分起源于外胚层。外胚层对运河的贡献过程尚不清楚。为了了解这一区域的发育，从胚胎13.0天(E13.0)到胚胎18.5天，每隔12小时进行一次连续的小鼠胚胎矢状面切片。从这些切片上获得三维重建图像。在泄殖腔膜消失时(E13.5)，内皮衬达到崩解膜的位置。因此，整条运河都有内胚层起源。初生会阴的背端较其他外胚层上皮厚，在这一过渡区由锐角变为钝角。待其拉直并形成管状后，二次会阴尾部出现。在这些过程中，外括约肌出现在厚外胚层的下层间质中，并起到牵引线的作用，形成外胚层肛管。