Placenta Looks Like a Tree
|Schematic representation of placental circulation|
The placenta is similar with a tree planted to a pot. As a tree takes deep root in the soil, the vessels from the umbilical cord, which inserts to the chorionic plate, stretch toward the intervillous space by progressively branching from intermediate villi to terminal villi. It finally forms several local regions called the 'cotyledon', consisting of villous trees, at the maternal surface called 'decidua basalis'. The intervillous space is filled with maternal blood and perfused through spiral arterioles, which enables the feto-maternal metabolic transports.