What does the allantois and yolk sac beacome?

The allantois eventually contributes to the formation of the umbilical cord and is involved in waste storage and gas exchange in embryos. The yolk sac primarily provides nutrients to the developing embryo early in gestation and later contributes to the formation of blood cells and the early circulatory system. As development progresses, both structures are largely absorbed or integrated into the developing fetus, losing their distinct roles.