What are the chorion and amnion in embryo development?

The chorion and amnion are cavities that form in the embryo on the seventh and eighth day of pregnancy, according to Discovery.com. The amnion is a light membrane sac containing amniotic fluid that allows the embryo to move freely. The chorion is a double-layered sac that houses the embryo.

According to Amniox Medical, the amniotic membrane is essential in protecting the fetus, as the membrane develops at the same pace as the child, allowing for a safe environment throughout the pregnancy.

Nature.com explains that it is common for the amnion and chorion membranes to separate from one another during the first trimester in many pregnancies. In certain cases, the separation may lead to abnormal chromosome development.