Kluth D, Hillen M, Lambrecht W
Department of Pediatric Surgery, University Hospital Hamburg, Germany.
J Pediatr Surg. 1995 Aug;30(8):1143-7. doi: 10.1016/0022-3468(95)90007-1.
In the past, several theories have been proposed to explain the occurrence of anorectal malformations. Most investigators believe that these malformations are the result of an impaired process of septation. However, in 1986 vd Putte challenged all theories that tried to explain anorectal malformations by a faulty fusion of lateral ridges of the cloaca. To elucidate the principles of normal and abnormal cloacal development, the authors studied the morphology of this region in normal embryos of rats and abnormal embryos of SD mice, which often have abnormal cloacas. Using scanning electron microscopy (SEM), 245 normal rat embryos and 80 abnormal SD-mice embryos were observed. The results were as follows. (1) In normal embryos the region of the future anal opening can be identified soon after the establishment of the cloacal membrane. This part is a fixed point in cloacal development. (2) In abnormal embryos the cloacal membrane is too short. The region of the future anal opening is missing. (3) In abnormal embryos a spectrum of malformed cloacas can be observed. This is in accordance with the spectrum of anorectal malformations clinically observed in humans. (4) The authors' observations support recent findings that the "fistula" in anorectal malformations resembles a normal anus at an ectopic position.
过去，人们提出了几种理论来解释肛门直肠畸形的发生。大多数研究者认为，这些畸形是分隔过程受损的结果。然而，1986年，vd Putte对所有试图通过泄殖腔侧嵴融合异常来解释肛门直肠畸形的理论提出了质疑。为了阐明正常和异常泄殖腔发育的原理，作者研究了正常大鼠胚胎和经常有异常泄殖腔的SD小鼠异常胚胎中该区域的形态。使用扫描电子显微镜（SEM），观察了245个正常大鼠胚胎和80个异常SD小鼠胚胎。结果如下。（1）在正常胚胎中，泄殖腔膜形成后不久就能识别出未来肛门开口的区域。这部分是泄殖腔发育中的一个固定点。（2）在异常胚胎中，泄殖腔膜太短。未来肛门开口的区域缺失。（3）在异常胚胎中，可以观察到一系列畸形的泄殖腔。这与临床上在人类中观察到的肛门直肠畸形谱一致。（4）作者的观察结果支持了最近的发现，即肛门直肠畸形中的“瘘管”类似于异位位置的正常肛门。
