When and where do chorionic villi appear in humans ? State their function.

Explanation

chorionic villi are finger-like projections that arises arise from the trophoblast layer that develops in the zygote after it has undergone implantation .
Function of cgorionic villi
1. these interdigiate with projections from uterine tissue to form a structure called the placenta , which is the
2. these facilitate the supply of oxygen and nutrients to the embryo.