What structure connects the developing fetus to the placenta?

The umbilical cord is the structure that connects the developing fetus to the placenta. It plays a crucial role in providing a vital link between the two, allowing for the transfer of nutrients, oxygen, and waste products. The umbilical cord contains two arteries and one vein. The arteries carry deoxygenated blood and waste from the fetus to the placenta, while the vein brings oxygenated blood and nutrients from the placenta back to the fetus. This connection is essential for the growth and development of the fetus during pregnancy.

In contrast, the amniotic sac is the structure that surrounds and protects the developing fetus, providing cushioning and maintaining a stable environment, but it does not connect the fetus to the placenta. Cord blood refers to the blood found in the umbilical cord and placenta, which can be collected for medical purposes, but it is not a structure that connects the fetus to the placenta. The placental barrier refers to the interface between maternal and fetal blood within the placenta, regulating substance exchange but is not a physical structure that connects the developing fetus directly to the placenta.