*4.2. Endovenous Trophoblast*

Following invasion into uterine glands, it seems as if the next route of invasion guides extravillous trophoblasts toward uterine veins (Figure 2A) [24–26]. The secretion products of the uterine glands need to be removed from the growing intervillous space. With the invasion of uterine veins by endovenous trophoblasts and the connection of the veins to the placenta, this removal is assured

(Figure 2A). The connection of the veins prior to the connection of the arteries is physiologically allegeable as removal of the blood plasma flowing into the placenta needs to be secured prior to floating of the intervillous space (Figure 2B). As outlined above, respective findings have been obtained already during very early stages of placentation [22].
