Placenta
The placenta anchors the embryo in the uterus.It also allows: 1. Nutrients and oxygen to move from the mother to the embryo. 2. Waste materials and carbon dioxide to move from the embryo to the mother. 3. There is no physical connection between the circulatory systems of the embryo and its mother, so their blood doesn’t mix. These materials pass from one to the other by diffusion.