Chorion

Definition

The chorion is an outer fetal membrane in amniotic eggs, including those of reptiles. It plays a crucial role in gas exchange between the embryo and the external environment.

5 Must Know Facts For Your Next Test

1. The chorion lies just beneath the eggshell and works in conjunction with the allantois for respiratory functions.
2. It helps facilitate the exchange of oxygen and carbon dioxide between the embryo and its surroundings.
3. In reptiles, the chorion is part of a complex system that allows development within an egg laid on land.
4. The chorion can fuse with other membranes, such as the allantois, to form structures like the chorioallantoic membrane.
5. It provides structural support to the developing embryo by maintaining integrity during gestation.

Review Questions

• What is the primary function of the chorion in reptilian eggs?
• How does the chorion contribute to respiratory functions in reptile embryos?
• Why is the chorion important for embryos developing inside eggs laid on land?

Related terms

Amnion:

The innermost membrane that encloses the embryo, providing a protective amniotic fluid-filled cavity.

Allantois:

An extra-embryonic membrane involved in gas exchange and waste storage during embryonic development.

Yolk Sac:

A membranous sac attached to an embryo, providing early nourishment through yolk before placental circulation takes over.