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How are the fetal and maternal sides of the placenta different?
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Devices for individual use at home detect pregnancy by measuring levels of the hormone human chorionic gonadotropin (hCG) in urine.
The placenta is a complex organ composed of distinct fetal and maternal components that facilitate the exchange of nutrients, gases, and waste between the mother and the developing fetus.12
The two sides of the placenta differ significantly in their appearance and composition:
- Fetal Side: This surface is smooth, shiny, and covered by the amnion. It is characterized by a network of branching fetal blood vessels that converge at the point where the umbilical cord attaches. This side is derived from the chorion frondosum, which contains the villi—treelike structures that extend into the maternal blood to facilitate metabolic exchange.12
- Maternal Side: This side is formed from the decidua basalis, a specialized portion of the uterine lining. It has a rough, purplish-red, and raw appearance. It is divided into 15 to 20 compartments known as cotyledons, which are separated by partitions projecting from the decidual tissue.1
While these two sides interact to support the fetus, they remain separated by the placental barrier, ensuring that maternal and fetal bloodstreams do not mix.12