Placenta: Fetomaternal organ of metabolic interchange between the embryo or fetus and mother. It has a portion of embryonic origin, derived from a highly developed area of the outermost embryonic membrane (chorion frondosum), and a maternal portion formed by a modification of the part of the uterine mucosa (decidua basalis) in which the chorionic vesicle is implanted. Within the placenta, the chorionic villi, with their contained capillaries carrying blood of the embryonic circulation, are exposed to maternal blood in the intervillous spaces in which the villi lie; no direct mixing of fetal and maternal blood occurs, but the intervening tissue (the placental membrane) is sufficiently thin to permit the absorption of nutritive materials, oxygen, and some harmful substances, like viruses, into the fetal blood and the release of carbon dioxide and nitrogenous waste from it. At term, the human placenta is disc shaped, about 4 cm in thickness and 18 cm in diameter, and averages about 1/6-1/7 the weight of the fetus; its fetal surface is smooth, being formed by the adherent amnion, with the umbilical cord normally attached near its center; the maternal surface of a detached placenta is rough because of the torn decidual tissue adhering to the chorion and shows lobular elevations called cotyledons or lobes. [L. a flat cake]
Source: Stedman's Medical Spellchecker, © 2006 Lippincott Williams & Wilkins. All rights reserved.
Placenta: The organ that nourishes the developing fetus in the uterus.
Source: National Institute of Health
Placenta: the vascular structure in the uterus of most mammals providing oxygen and nutrients for and transferring wastes from the developing fetus.
Source: WordNet 2.1
Placenta: highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products; it includes a fetal portion, the chorionic villi, and a maternal portion, the decidua; the placenta produces an array of steroid, protein and peptide hormones.
Source: CRISP
Placenta: A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (CHORIONIC VILLI) derived from TROPHOBLASTS and a maternal portion (DECIDUA) derived from the uterine ENDOMETRIUM. The placenta produces an array of steroid, protein and peptide hormones (PLACENTAL HORMONES).
Source: MeSH 2007
Placenta (organ): Organ connecting fetus to the mother's uterus.
Placenta (organ): See Placenta (organ information).
More information on organs: Placenta:
Source - MeSH 2007
Source - MeSH 2007
Source - MeSH 2007
Source - WordNet 2.1
Source - CRISP
Source - WordNet 2.1
Source: CRISP
The following list attempts to classify Placenta into categories where each line is subset of the next.
Source: WordNet 2.1
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