The growth pattern of the human intestine and its mesentery

Abstract

BackgroundIt remains unclear to what extent midgut rotation determines human intestinal topography and pathology. We reinvestigated the midgut during its looping and herniation phases of development, using novel 3D visualization techniques.ResultsWe distinguished 3 generations of midgut loops. The topography of primary and secondary loops was constant, but that of tertiary loops not. The orientation of the primary loop changed from sagittal to transverse due to the descent of ventral structures in a body with a still helical body axis. The 1st secondary loop (duodenum, proximal jejunum) developed intraabdominally towards a left-sided position. The 2nd secondary loop (distal jejunum) assumed a left-sided position inside the hernia before returning, while the 3rd and 4th secondary loops retained near-midline positions. Intestinal return into the abdomen resembled a backward sliding movement. Only after return, the 4th secondary loop (distal ileum, cecum) rapidly “slid” into the right lower abdomen. The seemingly random position of the tertiary small-intestinal loops may have a biomechanical origin.ConclusionsThe interpretation of “intestinal rotation” as a mechanistic rather than a descriptive concept underlies much of the confusion accompanying the physiological herniation. We argue, instead, that the concept of “en-bloc rotation” of the developing midgut is a fallacy of schematic drawings. Primary, secondary and tertiary loops arise in a hierarchical fashion. The predictable position and growth of secondary loops is pre-patterned and determines adult intestinal topography. We hypothesize based on published accounts that malrotations result from stunted development of secondary loops.Electronic supplementary materialThe online version of this article (doi:10.1186/s12861-015-0081-x) contains supplementary material, which is available to authorized users.

The fate of the vitelline and umbilical veins during the development of the human liver

“…) as well as our earlier study (Soffers et al. ) clearly document it to be a small left‐sided vein coming from the developing midgut mesentery and draining into the left vitelline vein. The main trunks of the vitelline veins themselves follow the stalk of the yolk sac and anastomose at several places ( cf .…”

“…G) and ceased to exist at ~ 35 days (Soffers et al. ). As a result, the transverse septum appeared to ‘rotate’ ~ 60° to assume its typical transverse orientation (Fig.…”

“…The growth of the proximal duodenum and associated dorsal mesentery results in the formation of the cranial secondary intestinal loop (Soffers et al. ). The ventral pancreas and associated common bile duct, in contrast, remained attached to the liver (and ventral mesentery) and did not change position.…”

The development of the cloaca in the human embryo

“…This extension results in a helical shape of the embryonic axis (Soffers et al. ). From CS14 onwards, the caudal region straightened (Fig.…”

Evaluation of First-Trimester Physiological Midgut Herniation Using Three-Dimensional Ultrasound

“…They showed 3D examination to be non-inferior to 2D examination, although this was not scientifically tested. Soffers et al [22], who investigated the rotation of the midgut in histological specimens, used another novel 3D visualisation technique in which serial sections of historical collections of embryos and fetuses were digitised using a scanning microscope. These images were subsequently converted and aligned to create a 3D reconstruction.…”