van der Putte S C J
Department of Pathology, University Medical Center Utrecht, Utrecht, The Netherlands.
Pediatr Dev Pathol. 2006 Jul-Aug;9(4):280-96. doi: 10.2350/06-01-0034.1.
Histopathological information about "anorectal malformations" is scarce and the pathogenesis still controversial. Autopsy specimens of 20 human fetuses and newborns with "main" types of the disorder were studied histologically. Supplemented with surgical-anatomical data from the literature and with information from our own and earlier embryological research in animal models as well as from recent observations on the normal development of the human perineum, the study allowed for a new reconstruction of the pathogenesis of the disorder. The histological analysis of the malformations in human fetuses and newborns showed a ventralward deviation of the anal canal as the principal deformity. Ano-urogenital communications and differently structured ectopic anocutaneous canals issued from anywhere between the bladder and the vestibular/urethral orifice (female urethra excluded) and between the orifice and the usual site of the anus, respectively, or they ended blindly, but with a suggestion of lost communication. They occurred isolated or in association with other primary or secondary regional anomalies. Patho-embryological data from animal models revealed that the deviation was caused by defective development of the dorsal cloaca and not by disturbances in a series of fusion processes inside and outside the cloaca, as is currently believed. This mechanism fits well into recent adjustments of ideas about the normal development of the perineum. The cause of the defect is still obscure, but a malfunctioning of cells ingressing from an end-stage primitive streak that affects the dorsal side of the prospective cloaca appears most likely. The data collected permit a new reconstruction of the pathogenesis of anal and ano-urogenital malformations.
关于“肛门直肠畸形”的组织病理学信息匮乏，其发病机制仍存在争议。对20例患有该疾病“主要”类型的人类胎儿和新生儿的尸检标本进行了组织学研究。结合文献中的外科解剖数据、我们自己以及早期在动物模型中的胚胎学研究信息，以及近期关于人类会阴正常发育的观察结果，该研究对该疾病的发病机制进行了新的重构。对人类胎儿和新生儿畸形的组织学分析显示，肛管向腹侧偏移是主要畸形。肛门泌尿生殖通道以及结构各异的异位肛门皮肤通道分别发自膀胱与前庭/尿道外口（不包括女性尿道）之间以及该外口与肛门通常位置之间的任何部位，或者它们盲端终止，但有失去连通的迹象。它们单独出现或与其他原发性或继发性区域异常相关。动物模型的病理胚胎学数据显示，这种偏移是由背侧泄殖腔发育缺陷引起的，而不是像目前所认为的那样由泄殖腔内、外一系列融合过程的紊乱所致。这一机制与近期关于会阴正常发育的观念调整相契合。缺陷的原因仍然不明，但最有可能的是，来自末期原始条带的细胞功能异常影响了未来泄殖腔的背侧。所收集的数据允许对肛门和肛门泌尿生殖畸形的发病机制进行新的重构。
