placenta: the thick plaque of tissue that forms when an embryo attaches itself to the inner wall of the womb, and which is joined to the baby by the umbilical cord [from Latin, placenta, flat cake].

Dictionary of Sexology Project: Main Index

The organ that serves as a filter and lifeline to a developing baby. It is what filters out nutrients from the mother's own blood and transfers it to the fetus's blood (since the two have their own independant blood supplies).

Foreign cultures as well as other mammals are known to eat the afterbirth to regain those nutrients that have been allocated for the purpose of gestation (as disgusting as this may sound, it makes sense is the placenta is rich in nutrients).

1. A structure formed on the wall of the uterus during pregnancy which serves to exchange oxygen, wastes and nutrients between the mother's blood and the embryo/fetus' blood; the placenta is expelled as afterbirth.
   
   There are several types of placentas:
   • hemochorial placenta
   • hemomonochorial placenta
   • hemoendothelial placenta
   
   
   
2. In plants: a region, within an ovary, to which ovules are attached.

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From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.

Pla*cen"ta (?), n.; pl. L. Placentae (#), E. Placentas (#). [L., a cake, Gr. a flat cake, from flat, fr. , , anything flat and broad.]

1. Anat.

The vascular appendage which connects the fetus with the parent, and is cast off in parturition with the afterbirth.

In most mammals the placenta is principally developed from the allantois and chorion, and tufts of vascular villi on its surface penetrate the blood vessels of the parental uterus, and thus establish a nutritive and excretory connection between the blood of the fetus and that of the parent, though the blood itself does not flow from one to the other.

2. Bot.

The part of a pistil or fruit to which the ovules or seeds are attached.

 

© Webster 1913.