Allantois

Definition

The allantois is an extra-embryonic membrane involved in the exchange of gases and handling of liquid waste in reptilian embryos. It plays a crucial role in the development and survival of the embryo within the egg.

5 Must Know Facts For Your Next Test

1. The allantois is one of four extra-embryonic membranes, along with the amnion, chorion, and yolk sac.
2. It functions primarily in respiration and excretion for the developing embryo.
3. In reptiles, it often fuses with the chorion to form the chorioallantoic membrane, which facilitates gas exchange.
4. The allantois stores nitrogenous wastes produced by the embryo during development.
5. It contributes to the formation of the umbilical cord in mammals but serves different functions in reptiles.

Review Questions

• What are the primary functions of the allantois in reptilian embryos?
• How does the allantois contribute to waste management for a developing reptile embryo?
• Which extra-embryonic membrane does the allantois typically fuse with in reptiles?

Related terms

amnion:

A fluid-filled extra-embryonic membrane that cushions and protects developing embryos.

chorion:

An outermost extra-embryonic membrane involved in gas exchange; often fuses with allantois.

yolk sac:

An extra-embryonic membrane that provides nutrition to developing embryos through yolk absorption.