Topographical anatomy of the greater omentum and transverse mesocolon: a study using human fetuses

The greater omentum covers the transverse colon from the anterior side in adults, but people might believe the morphology stable once established during fetal life. Sections from 49 midterm and 17 late-stage human fetuses, of gestational ages (GA) 8-15 and 30-38 weeks, respectively, showed complete fusion between the greater omentum and transverse mesocolon after physiological herniation at GA 8-9 weeks; the transverse colon attaching to the anterior aspect of the gastric antrum and pylorus at GA 10-15 weeks; the colon pushing the pylorus or superior portion of the duodenum upward (at GA 10-15 weeks and 30-38 weeks); and the greater omentum without covering the greater portion of the jejunum and ileum but shifted leftward (at GA 30-38 weeks). These subsequent topographical variations of the transverse colon with the stomach and duodenum included the colon tightly fusing with the stomach by a fibrous tissue and; the greater omentum and/or the mesocolon wedged between the stomach and transverse colon. Therefore, in combination, the colon was partly separated from the greater omentum. Moreover, at GA 30-38 weeks, the duodenum consistently showed a horizontal loop in contrast to the usual C-loop in the frontal plane. Consequently, after a complete fusion occurred once between the greater omentum and transverse mesocolon, the topographical change of the upper abdominal viscera seemed to modify, change or even break the initial fusion of the peritoneum. A logical lamination of the peritoneum seemed not to simply connect with the surgical application.