Department of Anatomy & Embryology, Maastricht University, P.O.Box 616, 6200MD, Maastricht, The Netherlands.
Department of Anatomy & Embryology, Maastricht University, P.O.Box 616, 6200MD, Maastricht, The Netherlands.
Semin Cell Dev Biol. 2019 Aug;92:18-26. doi: 10.1016/j.semcdb.2018.08.009. Epub 2018 Aug 25.
The vertebrate intestine has a continuous dorsal mesentery between pharynx and anus that facilitates intestinal mobility. Based on width and fate the dorsal mesentery can be subdivided into that of the caudal foregut, midgut, and hindgut. The dorsal mesentery of stomach and duodenum is wide and topographically complex due to strong and asymmetric growth of the stomach. The associated formation of the lesser sac partitions the dorsal mesentery into the right-sided "caval fold" that serves as conduit for the inferior caval vein and the left-sided mesogastrium. The thin dorsal mesentery of the midgut originates between the base of the superior and inferior mesenteric arteries, and follows the transient increase in intestinal growth that results in small-intestinal looping, intestinal herniation and, subsequently, return. The following fixation of a large portion of the abdominal dorsal mesentery to the dorsal peritoneal wall by adhesion and fusion is only seen in primates and is often incomplete. Adhesion and fusion of mesothelial surfaces in the lesser pelvis results in the formation of the "mesorectum". Whether Toldt's and Denonvilliers' "fasciae of fusion" identify the location of the original mesothelial surfaces or, alternatively, represent the effects of postnatal wear and tear due to intestinal motility and intra-abdominal pressure changes, remains to be shown. "Malrotations" are characterized by growth defects of the intestinal loops with an ischemic origin and a narrow mesenteric root due to insufficient adhesion and fusion.
脊椎动物的肠有一个连续的背系膜，位于咽和肛门之间，有助于肠的移动。根据宽度和命运，背系膜可以细分为尾前肠、中肠和后肠的背系膜。由于胃的强烈和不对称生长，胃和十二指肠的背系膜宽阔且具有复杂的地形。小网膜的相关形成将背系膜分隔成右侧的“腔静脉襞”，作为下腔静脉的通道，以及左侧的系膜。中肠的薄背系膜起源于肠系膜上动脉和肠系膜下动脉的根部之间，随着肠生长的短暂增加，导致小肠环、肠疝出，随后返回。只有在灵长类动物中，大部分腹部背系膜才会通过粘连和融合固定在背腹膜壁上，而且通常是不完全的。小骨盆内间皮表面的粘连和融合导致“系膜直肠”的形成。托尔特和德农维利耶的“融合筋膜”是否确定了原始间皮表面的位置，或者相反，是否代表了由于肠蠕动和腹腔内压力变化导致的出生后磨损的影响，仍有待证明。“旋转不良”的特点是肠环的生长缺陷，起源于缺血，肠系膜根狭窄，由于粘连和融合不足。
