Amniote embryo

Definition

An amniote embryo is an embryo that develops inside an amniotic egg, which provides a protective environment. This adaptation is crucial for terrestrial reproduction among vertebrates such as reptiles, birds, and mammals.

5 Must Know Facts For Your Next Test

1. Amniote embryos are characterized by the presence of extraembryonic membranes including the amnion, chorion, yolk sac, and allantois.
2. The amnion creates a fluid-filled cavity that cushions and protects the developing embryo.
3. Reptiles, birds, and mammals are all classified as amniotes because they produce amniotic eggs or have evolved from ancestors that did.
4. The evolution of the amniotic egg allowed vertebrates to lay eggs on land without desiccation threats.
5. Amniote embryos undergo direct development, meaning they do not have a larval stage.

Review Questions

• What are the extraembryonic membranes found in an amniote embryo?
• Why is the evolution of the amniotic egg significant for terrestrial reproduction?
• Which groups of vertebrates are classified as amniotes?

Related terms

Amnion: A membrane forming a fluid-filled cavity that surrounds and protects the embryo.

Chorion: The outermost membrane around an embryo that contributes to gas exchange.

Allantois: An extraembryonic membrane involved in waste storage and gas exchange.