Final answer:
The embryo is attached to the mother's blood supply through the placenta and the umbilical cord.
Step-by-step explanation:
The embryo is attached to the mother's blood supply through the placenta and the umbilical cord.
The placenta is a spongy mass of blood vessels that connects to the mother's uterus and allows for exchange of substances between the mother's blood and the fetal blood. The umbilical cord, which contains two arteries and a vein, connects the fetus to the placenta.