the outermost membranous sac enclosing the embryo in higher vertebrates (reptiles, birds and mammals)
例句
用作名词 (n.)
A chorionic villus is a minute vascular projection on the fetal chorion. 绒膜绒毛是胎儿绒毛膜上的一种微小的血管凸出物。
After implantation of the blastocyst in the uterine wall the trophoblast divides into two layers, the chorion and the placenta. 在胚泡植入子宫壁后，胚胎滋养层分成两层，即绒毛膜和胎盘。
美
['koʊrɪˌɒn]
