What is a placental cotyledon:: (A) All branches from one stem villi, (B) Area supplied by one spiral aery, (C) Quaer of placenta, (D) Area drained by one terminal villi
Answer is A. Functional unit of the placenta is called a fetal cotyledon or placentome,which is derived from a major primary stem villus. These stem villi pass down through the intervillous space to anchor onto the basal plate.About 60 stem villi persist in human placenta. Thus each cotyledon(totalling 15-29) contains 3-4 major stem villi. Reference : Dutta Textbook of Obstetrics &th edition page no 31