Fig. 3
From: The growth pattern of the human intestine and its mesentery
Descent of the ventral organs during the 5th and 6th week moves the proximal limb of the primary midgut loop rightward. Panel a: Descent of structures in the upper abdomen between CS14 and CS18 relative to the intersegmental arteries. Intersegmental artery 7 identifies vertebra C7. Panels b and c: Dorsal views of reconstructions of a CS14 (s5029) and a CS16 (s5032) embryo, respectively, with the notochord (1) and neural tube (NT) aligned in their medial portions. Inset: notochord alone. The helical alignment of the body axis has largely resolved at CS16. Panels d and e: Right-sided views of reconstructions of the intestine at CS15 (2213) and CS16 (s5032), respectively. The cranial end of the dorsal midgut mesentery is identified by number 9. The right vitelline vein (7), the vitelline/SMA (3), and the periductal mesenchyme (8) mark the apical portion of the midgut. The umbilical orifice is indicated by a dashed oval. The plane through the orifice changed with the straightening of the body (bold arrow in panel d). Note that the descent of the ventral organs moves the proximal limb of the midgut loop to a more rightward and dorsal position. The orange numbers identify intersegmental artery #15 (corresponding to vertebra Th8). Scale bar unit: μm. An interactive 3D-PDF is available online (3D-PDF CS16)