What is a placental cotyledon?
All branches from one stem villi
Area supplied by one spiral aery
Quaer of placenta
Area drained by one terminal villi
Each of the truncal or main stem villi and their ramifications constitutes a placental lobule or cotyledon. Each lobule is supplied with a single truncal branch of chronic aery. And each lobule has a single vein so that lobules constitute functional units of placental architecture. Ref: Williams 24e pg 94.
General obstetrics