Dictionary of Human Evolution and Biology

  • -id > 9:3


Membranous sac outside the body of the embryo that develops out of the yolk sac. In oviparous animals it serves as a waste repository, but in mammals it functions in the formation of blood cells during the embryo stage. Later the blood vessels of the allantois become the umbilical blood vessels. The allantois also contributes to the formation of the urinary bladder.

See angiogenesis.

Full-Text Search Entries

Suggestions from Other Sources

From "Dictionary of Nursing and Individual Health Care"