1.2绒毛膜、体蒂 卵黄囊 血管一·3套循环线毛膜 胚体 胚体 Ant Common cardinal vein cardinal vein Dorsal aorta Aortic arches (ll and Ill) Post. cardinal vein carotid Chorionic artery l Heart Aortic sac Vitelline vein Chorion Vitelline Umbilical vein artery and artery1.2 绒毛膜、体蒂 胚体 血管 3 套循环 卵黄囊 绒毛膜 胚体