Cellular processes involved in asymmetric midgut rotation. (A) The primitive gut is divided into foregut (yellow), midgut (blue), and hindgut (brown). Primary midgut loop forms due to rapid midgut growth with respect to the embryo (1). (2) The loop rotates 90° counterclockwise (ventral view). (3) Additional loops form as the gut rotates another 180°. (B) The mechanisms that lead to midgut rotation (2 in A). The midgut is suspended by the DM, which comprises four distinct cell compartments, and changes within each cause the DM to deform and tilt the gut tube leftward. Transcriptional regulation of Wnt pathway genes by Pitx2 leads to Daam2 activation, which mediates adhesion at cell junctions by binding α-catenin and N-cadherin. Actin remodeling and lengthening of junctions cause left condensation. Antagonized Wnt signaling causes right mesenchymal cells to remain dispersed. Shroom3 with N-cadherin on the left are also involved in the conversion of cuboidal to columnar cell morphology. Consequently, the left DM shortens, and the right side lengthens, deforming the DM and shifting midgut leftward. Left compartment is orange; right is green. Midgut is blue.