During gestation the ductus venosus shunts most of the blood from the umbilical vein directly into the inferior vena cava. Shortly after birth the ductus venosus closes to allow normal circulation. It usually closes completely within the first week after birth, but can take longer in pre-term infants. After it is closes a small remnant remains and is called the ligamentum venosum.
Umbilical Arteries Placenta Umbilical Vein Ductus Venosus Foramen Ovale Ductus Arteriosus
The most fetal blood in the umbilical vein enters the inferior vena cava through the ductus venosus.
The Ductus Venosus
The foramen ovale is a hole in the heart that allows blood to bypass the lungs in a developing fetus. The ductus venosus is a blood vessel that connects the umbilical vein to the inferior vena cava, allowing oxygen-rich blood from the placenta to bypass the liver in a fetus.
In fetal circulation, the ductus arteriosus is a connective vessel between the pulmonary artery and aorta. It works as to bypass the lungs, which are collapsed in the womb. After birth, the ductus arteriosus normally closes.
another fetal structure ?
The ductus venosus shunts most of the left umbilical vein blood flow directly to the inferior vena cava. This allows relatively highly oxygenated blood from the placenta to bypass the liver and get to the fetal brain.
Ductus arteriosus
In the fetus, the ductus venosus shunts a significant majority (80%) of the blood flow of the umbilical vein directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. In conjunction with the other fetal shunts, the foramen ovale and ductus arteriosus, it plays a critical role in preferentially shunting oxygenated blood to the fetal brain.Source(s):http://en.wikipedia.org/wiki/Ductus_veno…
Increase
Because the fetal lungs are inactive, the pulmonary circuit is bypassed. Half of the blood that enters the right atrium flows directly into the left atrium through the foramen ovale. The remainder flows from the right atrium to the right ventricle, then into the pulmonary trunk. The second bypass, the ductus arteriosus, transports the blood directly from the pulmonary artery into the aorta so it can be sent into systemic circulation.
The ductus venosus.