ETYM Latin, a cake, Greek placoenta a flat cake, from plax, anything flat and broad.
Mammal's organ attached to and nourishing fetus in womb; afterbirth. Organ that attaches the developing embryo or fetus to the uterus in placental mammals (mammals other than marsupials, platypuses, and echidnas). Composed of maternal and embryonic tissue, it links the blood supply of the embryo to the blood supply of the mother, allowing the exchange of oxygen, nutrients, and waste products. The two blood systems are not in direct contact, but are separated by thin membranes, with materials diffusing across from one system to the other. The placenta also produces hormones that maintain and regulate pregnancy. It is shed as part of the afterbirth.
It is now understood that a variety of materials, including drugs and viruses, can pass across the placental membrane. hiv, the virus that causes aids, can be transmitted in this way.
The tissue in plants that joins the ovary to the ovules is also called a placenta.
1. That part of the ovary of a flowering plant where the ovules form.
2. The vascular structure in the uterus of most mammals providing oxygen and nutrients for and transferring wastes from the developing fetus. + prikaži više