Question

What are the finger-like projections of the outer embryonic layer that penetrate the uterine wall called?

Options

• Amnion folds

• Trophoblastic plugs

• Chorionic villi

• Decidual cells

Answer 1

Chorionic villi are finger-like projections of the trophoblast (outer layer of the embryo) that develop after implantation. These villi penetrate and become surrounded by uterine tissue and maternal blood, becoming interdigitated with the uterine tissue to form the placenta.