What does the ductus venosus connect to in fetal circulation?

The ductus venosus is a crucial structure in fetal circulation, functioning as a shunt that directs blood from the umbilical vein directly into the inferior vena cava. This allows oxygen-rich blood from the placenta to bypass the liver, which is not yet fully functional in the fetus. By connecting the umbilical vein to the inferior vena cava, the ductus venosus ensures that a significant portion of the highly oxygenated blood reaches the right atrium of the heart, promoting efficient delivery of oxygen to the developing fetus.

Understanding this connection is important as it highlights the unique adaptations in fetal circulation that differ from postnatal circulation, where structures such as the ductus venosus close after birth, transforming the circulatory pathway in response to the infant's independent respiration and nutrient intake.