We have the umbilical vein shown in red and we have umbilical arteries shown in blue. So the umbilical arteries carry deoxygenated blood that contains carbon dioxide from the organs and tissues of that fetus and to the placenta itself. And it carries them to these Corianic villi, these extensions of the Coriane known as the corionic villi. And within the Corianic villi, we have the tiny blood capillaries that belong to the circulatory system of that fetus. Now, these entire Corianic villi are found inside a pool of maternal blood. And that pool of maternal blood essentially oozes out of these maternal blood vessels that are found in close proximity.