chorionic villus

https://doi.org/10.1351/goldbook.10519

Any of the tiny extensions from the chorion that contain fetal blood vessels and combine with the uterine tissue to form the placenta.

Source:
PAC, 2016, 88, 713. (Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)) on page 735 [Terms] [Paper]