Amnion vs. Chorion — What's the Difference?

The amnion is a membrane that closely covers the human and various other embryos when first formed. It fills with amniotic fluid, which causes the amnion to expand and become the amniotic sac that provides a protective environment for the developing embryo.

The chorion is the outermost fetal membrane around the embryo in mammals, birds and reptiles (amniotes). It develops from an outer fold on the surface of the yolk sac, which lies outside the zona pellucida (in mammals), known as the vitelline membrane in other animals.

A tough, thin membrane that forms a sac enclosing the embryo or fetus of a mammal, bird, or reptile. It is filled with a serous fluid in which the embryo or fetus is suspended.

The outer membrane enclosing the embryo in reptiles, birds, and mammals. In placental mammals it contributes to the development of the placenta.

(anatomy) The innermost membrane of the fetal membranes of reptiles, birds, and mammals; the sac in which the embryo is suspended.

The protective and nutritive membrane in higher vertebrates that attaches the fetus to the uterus.

A thin membrane surrounding the embryos of mammals, birds, and reptiles.

The outer case of an insect egg.

Thin innermost membranous sac enclosing the developing embryo of higher vertebrates (reptiles, birds and mammals)

(botany) The outer membrane of seeds of plants.

The outer membrane which invests the fetus in the womb; also, the similar membrane investing many ova at certain stages of development.

The outer membrane of seeds of plants.

Outermost membranous sac enclosing the embryo in higher vertebrates (reptiles, birds and mammals)