Formation of Extra-Embryonic Membranes

What is the primary function of the yolk sac during embryonic development?

Which extra-embryonic membrane is primarily responsible for protection against mechanical injury?

In which layer does the chorion belong?

How does the allantois contribute to embryonic development?

What happens to the yolk sac as embryonic development proceeds?

What is the primary composition of the yolk sac?

Which extra-embryonic membrane is closely associated with gas and water exchange during development?

What significant development occurs as the embryo grows in relation to the allantois?

Which of the following extra-embryonic membranes is formed first during embryonic development?

What is the function of the amniotic sac surrounding the embryo?

During what stage does the allantois begin to develop in relation to the hindgut?

What role does the chorion play in relation to the inner shell membrane during development?

What alteration occurs to the yolk stalk as the embryo develops?

What is the significance of the extra-embryonic membranes being discarded at birth?

Which extra-embryonic membrane is directly involved in covering the yolk?

Formation of Extra-Embryonic Membrane

Extra-embryonic membranes arise from the peripheral germ layer, providing protection and nutrition from maternal blood.
These membranes are not integrated into the embryo, allowing them to be discarded at birth.

Classification of Extra-Embryonic Membranes

Yolk Sac:
- Originates from splanchnopleure.
- Part of the primitive gut; does not include the embryo's body.
- Directly covers the yolk, absorbing nutrients for the embryo.
Amnion:
- Derived from somatopleure.
- Attached where the body wall opens ventrally to the yolk stalk.
- Protects the embryo from mechanical injury through the amniotic sac.
Chorion:
- The outer layer of somatopleure.
- Rapidly expands, closely apposing the inner shell membrane by 7-8 days of incubation in chicks.
- Works with the allantois for gas and water exchange.
Allantois:
- Develops from the hindgut of the embryo as a diverticulum.
- Takes over metabolic functions from the yolk sac for maternal-fetal nutrient exchange.
- Grows larger as the yolk sac diminishes throughout development.

Formation of Extra-Embryonic Membranes

Extra-embryonic membranes protect the embryo and secure nutrients from the maternal blood.
Classified as extra-embryonic because they are not part of the embryo and are discarded at birth.

Types of Extra-Embryonic Membranes

Yolk Sac
- Derived from splanchnopleure.
- Part of the primitive gut, not part of the embryo's body.
- Absorbs nutrients from the uterus and covers the yolk.
- Acts as a nutritive organ for the embryo.
Amnion
- Derived from somatopleure.
- Attached to the embryo's body where it opens ventrally to the yolk stalk.
- The opening reduces during development to form the umbilical ring.
- Provides protection against mechanical injuries through the amniotic sac.
Chorion
- The outer layer of somatopleure.
- Expands rapidly, closely opposing the inner shell membrane by 7-8 days into incubation in chicks.
- Works with the allantois to facilitate gas and water exchange.
Allantois
- A diverticulum emerging with the establishment of the embryo's hindgut.
- Takes over the yolk sac functions for metabolic interchange between fetus and mother.
- The yolk sac shrinks while the allantois enlarges as development progresses.

This quiz examines the formation and function of extra-embryonic membranes, which play crucial roles in protection and nutrition of the embryo. Key membranes such as the yolk sac and amnion are discussed, highlighting their origins and significance during development. Test your knowledge on these important concepts and their classifications.