A section through the T-7 neural crest, L-5 somite and the urorectal septum.
Observe:
1. The proximal part of the lower buds with the origin of the right axial artery from the common iliac artery.
2. The junction of the umbilical and common iliac arteries.
3. The mesodermal urorectal septum separating the hindgut from the cloaca.
4. The left mesonephric duct in two locations.
5. Somatic mesoderm in the abdominal wall.
Keywords: L-5 somite, T-6 dermatome, T-7 dermatome, T-7 neural crest, axial artery, cloaca, coelom, dorsal aorta, ectoderm, hindgut, junction of right umbilical and common iliac arteries, lateral mesoderm (somatic), lateral segmental artery, left mesonephric duct, lower limb bud, median sacral artery, mesonephric duct, mesothelium, neural tube, notochord, postcardinal vein, right umbilical plexus, urorectal septum
Source: Atlas of Human Embryos.