\pləsˈɛntə], \pləsˈɛntə], \p_l_ə_s_ˈɛ_n_t_ə]\
Definitions of PLACENTA
- 2006 - WordNet 3.0
- 2011 - English Dictionary Database
- 2010 - New Age Dictionary Database
- 1913 - Webster's Revised Unabridged Dictionary
- 2010 - Medical Dictionary Database
- 1920 - A practical medical dictionary.
- 1898 - Warner's pocket medical dictionary of today.
- 1899 - The american dictionary of the english language.
- 1914 - Nuttall's Standard dictionary of the English language
- 1874 - Etymological and pronouncing dictionary of the English language
- 1920 - A dictionary of scientific terms.
- 1846 - Medical lexicon: a dictionary of medical science
- 1898 - American pocket medical dictionary
- 1916 - Appleton's medical dictionary
- 1871 - The Cabinet Dictionary of the English Language
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By Princeton University
By DataStellar Co., Ltd
By Oddity Software
By Noah Webster.
By DataStellar Co., Ltd
1. The organ of communication between the fetus and the mother; it is formed from the outer layer of the fetal envelopes, or chorion, and is of flat circular form, about the size of a soup-plate, or seven inches in diameter. The fetal surface is smooth and from it proceeds the umbilical cord; the maternal surface is marked by a number of lobules, or cotyledons, which project into sinuses in the wall of the uterus, being there bathed in the maternal blood; by this means the fetal blood receives oxygen and nutriment and gives up waste material, the placenta therefore performing the functions of respiration, nutrition, and excretion. After the expulsion of the child the placenta is called the after-birth. 2. An enlarged spleen, a clot, or other body having a resemblance to a placenta. 3. In botany, the sporophore, the part of the ovary of a plant which contains the ovules.
By Stedman, Thomas Lathrop
By William R. Warner
By Daniel Lyons
By Nuttall, P.Austin.
By Stormonth, James, Phelp, P. H.
The ovule-bearing part of the carpel; in eutherian Mammals, a double vascular spongy structure formed by interlocking of foetal and maternal tissue in the uterus, and in which maternal and foetal blood are in close proximity, allowing nutritive and respiratory elements to pass from the former to the latter by osmosis.
By Henderson, I. F.; Henderson, W. D.
A soft, spongy, vascular body, adherent to the uterus, and connected with the foetus by the umbilical cord. It is not in existence during the first period of the embryo state, but its formation commences perhaps with the arrival of the embryo in the uterus. It is generally considered to have two portions, one foetal, and the other maternal. The foetal consists of highly vascular villi and tufts, which contain the inosculating loops of the umbilical arteries and umbilical vein of the foetus. The maternal portion is considered by Dr. Reid to consist, essentially, of a large sac formed by the inner coat of the vascular system of the mother, into which the maternal blood is poured by the curling arteries of the uterus, and from which it is returned by the utero-placental veins. The tufts and villi of the foetal placenta are ensheathed by this inner coat of the maternal vascular system; and, according to Prof. Goodsir, two distinct sets of nucleated cells- one maternal and the other foetal-separate the maternal and foetal portions where they come in contact, one set of which are probably, he thinks, concerned in the separation of nutritive matter from the maternal blood, and the other destined to convey it into the vessels of the foetus. The placenta is formed of several lobes or cotyledons, which can be readily distinguished from each other on the uterine surface; but towards the foetal surface are confounded into one mass. It is composed of the umbilical vessels, areolar tissue, and whitish, resisting filaments, which are vascular ramifications obliterated. Lymphatic vessels have also been presumed to exist in it; and nerves have been traced, proceeding from the great sympathetic of the foetus. The main function of the placenta appears to be like that of the lungs in the adult. It admits of the blood of the foetus being shown to that of the mother, and undergoing requisite changes. It may, also, be an organ for nutritive absorption, as observed above. Animals, which have no placenta-as the Marsupialia-are called implacental and nonplacental.
By Robley Dunglison
By Willam Alexander Newman Dorland
Syn.: hepar uterinum. The afterbirth; an organ which during fetal life, in nearly all mammals, performs the function of aerating the blood of the fetus by providing the mechanism necessary to a direct interchange of gases between the fetal and the maternal blood; consisting of a maternal portion (see maternal p.) and a fetal portion (see fetal p.) closely interwoven with each other, the whole organ, thus doubly constructed, being intimately connected with the internal organism by its implantation upon the interior of the uterine wall on the one hand and connected with the fetal circulation by the umbilical cord on the other.
By Smith Ely Jelliffe