Question

The cellular, outermost extraembryonic membrane, composed of trophoblast lined with mesoderm. It develops villi about two weeks after fertilization. At three weeks, it is vascularized by allantoic vessels. This describes the ______.

a) Amnion
b) Chorion
c) Yolk sac
d) Placenta

Answer 1

The chorion is the cellular, outermost extraembryonic membrane that develops villi and becomes vascularized. It is one of the embryonic membranes that support and protect the growing embryo.

Step-by-step explanation:

The cellular, outermost extraembryonic membrane, composed of trophoblast lined with mesoderm is called the chorion. It develops villi about two weeks after fertilization and becomes vascularized by allantoic vessels at three weeks. The chorion is one of the embryonic membranes that support and protect the growing embryo, along with the amnion, yolk sac, and allantois.