No function in adult
This is the adult anatomic footprint of the normal path of oxygenated blood from the uterus
to bypass the fetal lungs & provide oxygen
to the fetus's body.
This path is in the wall between the fetus's left & right atria. At birth, this hole immediately closes, putting baby blood in the lungs. In adults, this closure may not be complete (patent for amen ovale) & blood may shunt across the atria.