The embryology of gut rotation

Until today, the puzzling spectrum of midgut "malrotations" is commonly explained by an "impaired" process of rotation of the midgut. However, a closer look at the literature reveals that the description of this "process of rotation" is rather schematic and is aimed more at explaining pathological findings, while detailed proper embryological investigations are still rare. Despite recent trials, good animals models that would allow the comparison of normal and abnormal midgut development are still missing. In the first part of this article, the "normal process of rotation," as it is described in the literature, is presented and critically analyzed. In general, it is a shortcoming that reliable illustrations of these crucial embryological processes are missing in most of these papers. Therefore, in the second part of this review scanning electron microscopy pictures of the developing midgut are presented in a series of rat embryos. In these pictures clear signs of a process of rotation are missing.