A section through the L-1 spinal ganglion and the cranial edge of the junction of the umbilical cord and the ventral body wall.
Observe:
1. The umbilical vein leaving the umbilical cord and the junction of the superior mesenteric veins.
2. The cranial major calyx of the primitive renal pelvis seen in Section 45.
3. The superior mesenteric vessels in the dorsal mesentery passing to the right and ventral to the caudal segment of the duodenum.
4. The subcardinal vein segment that will form the gonadal vein and the inferior vena cava segment that develops from the anastomosis between the right supra- and subcardinal veins.
5. The inferior mesenteric ganglion ventral to the aorta.
Keywords: L-1 spinal ganglion, aorta, cranial limb of midgut, cranial major calyx, dorsal mesentery, duodenum (caudal part), edge of dorsal mesentery, edge of stomach, erector spinae muscle group, gonad, inferior mesenteric ganglion, inferior vena cava (supracardinal-subcardinal segment), junction of umbilical cord and body wall, lesser sac, mesonephric artery, mesonephric duct, mesonephric glomerulus, mesonephric tubule(s), quadratus lumborum muscle, subcardinal vein (gonadal), superior mesenteric artery, superior mesenteric vein, sympathetic trunk, transversospinal muscle group, umbilical extension of peritoneal cavity, umbilical vein, vitelline (omphalomesenteric) vein
Source: Atlas of Human Embryos.