Illustration of the foetal surface of a triplet placenta with three separate umbilical cords. No septa are noted and thus each of the placentas have fused forming a single mass with vascular and metabolic communications. When all three foetuses share a placenta they are classified as monochorionic triplets. The paired umbilical arteries (red) pass from the foetus to the placenta and are depleted in oxygen and nutrients. The umbilical vein (blue) supplies oxygenated and nutrient-rich blood from the placenta to the foetus. From Kollmann, J. (1907) Handatlas der Entwicklungsgeschichte des Menschen, vol 1, Fig. 176. G. Fischer, Jena.