Question

List the significance of extra-embryonic membranes.

Answer 1

The extra-embryonic membranes support, protect and help nourish the developing embryo.

1. Amnion: Surrounds the embryo and encloses amniotic fluid, which prevents drying and cushions the embryo against mechanical shocks.
2. Yolk sac: In humans, it does not provide yolk nutrition; in early development it supplies stem cells that give rise to blood and lymphoid cells.
3. Chorion: Forms chorionic villi that contribute to the foetal part of the placenta and enable exchange between maternal and foetal blood across placental tissues.
4. Allantois: Contributes to the blood vessels of the umbilical cord and, with the chorion, helps form the foetal part of the placenta.