Figure 3

Human placental hemochorial placentation. While hCG and hyperglycosylated hCG force villous trophoblast tissue formation [13–17], hCG promotes the development and growth of uterine spiral arteries [19–26]. Angiogenesis forces the protrusion of arteries to reach invading villous trophoblast tissue [19–26]. hCG also promotes the formation of the umbilical circulation in villous tissue and the formation of the umbilical cord [27–32]. All linked together, villous trophoblast tissue, maternal spiral artery blood and fetal umbilical circulation and you have hemochorial placentation, efficient fetal nutrient exchange, as illustrated. In hemochorial placentation, spiral artery bring maternal blood into one of 4-7 hemochorial placentation chambers. Blood fills the chamber, nutrients (oxygen/glucse/amino acids) them pass across syncytiotrophoblast cells into villous side-arms or floating villi. They are then rapidly absorbed by the umbilical circulation.