placen'ta

[L. a cake.] i. 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. i. 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, abla'tio placen'tse, abrup'tio placen'tae, premature detachment of a normally situated placenta, acce 'ory p., a ma of placental ti ue distinct from the main placenta and sometimes at quite a distance from it. ann'ular p., one in the form of a band encircling more or le completely the interior of the uterus, batt'ledore p., one in which the fun is is attached at the border, fe'tal p., the portion composed of the chorion which contains the blood-ve els of the fetus, horse's hoe p., an exaggerated p. reniform is curved in the form of a horseshoe, mater'nal p., the thin mem- ' brane lining the p., formed of the decidua serotina. p. bi'lob a, a p. duplex in which the two parts are separated by a constriction, p. bi- . parti'ta, p. biloba. p. circumvalla'ta, a cup shaped placenta with raised edges; see p. refiexa. p. dimidia'ta [L. dimidiare, to divide into halves], p. duplex, p. du'plex, one consisting of two parts, almost entirely detached, being united only at the point of attachment of the cord. p. febri'lis, the enlarged spleen in chronic malaria, p. fenestra'ta, one in which there are areas of thinning, sometimes extending to entire absence of placental ti ue, p. fetal is, p. foeta'- lis [BNA], fetal p., the chorionic portion of the p., containing the fetal blood-ve els, p. marglna'ta, a p. with raised edges, le pronounced