What is the name of the membrane-covered bundle of blood vessels that connects a baby to the placenta?

The umbilical cord is the structure that serves as the lifeline between the developing baby and the placenta. It is composed of a bundle of blood vessels, typically two umbilical arteries and one umbilical vein, all surrounded by a protective gelatinous substance known as Wharton's jelly. This cord is crucial for the transfer of oxygen and nutrients from the placenta to the fetus, while also carrying waste products away from the developing baby back to the placenta for elimination.

Understanding the umbilical cord's role highlights its importance in fetal development, as it provides the necessary support for the baby by ensuring that all essential exchanges between mother and child take place effectively. The other options listed do not serve this particular function: the amniotic sac contains the amniotic fluid that cushions the fetus; a vascular bundle refers to a plant structure for transport; and a fetal ligament involves surrounding structures but does not connect the fetus to the placenta.