Dorsal aorta

Each primitive aorta receives anteriorly a vein—the vitelline vein—from the yolk-sac, and is prolonged backward on the lateral aspect of the notochord under the name of the dorsal aorta.

The dorsal aortæ give branches to the yolk-sac, and are continued backward through the body-stalk as the umbilical arteries to the villi of the chorion.

The two dorsal aortae combine to become the descending aorta in later development.