placenta
/pləˈsɛntə
/noun (plural placentae /pləˈsɛntiː/ or placentas)
1A flattened circular organ in the uterus of pregnant eutherian mammals, nourishing and maintaining the fetus through the umbilical cord.Causes of spontaneous abortion may relate to the fetus, the placenta, or the uterus....
- This transformation is essential to ensure a normal blood supply to the fetus and placenta throughout pregnancy.
- In each later pregnancy, maternal Rh antibodies can cross the placenta and reach the fetus.
The placenta consists of vascular tissue in which oxygen and nutrients can pass from the mother’s blood into that of the fetus, and waste products can pass in the reverse direction. The placenta is expelled from the uterus at the birth of the fetus, when it is often called the afterbirth. Marsupials and monotremes do not develop placentas.
2 Botany (In flowers) part of the ovary wall to which the ovules are attached.The entire placenta with attached ovules was removed via a longitudinal incision in the ovary wall....
- As the ovary elongates only above the placenta, the ovules appear basal at anthesis.
- The ovary has axile intruded placentae with around 250-350 ovules.
Origin
Late 17th century: from Latin, from Greek plakous, plakount- 'flat cake', based on plax, plak- 'flat plate'.