| placental hormones | Hormones produced by the placenta during pregnancy, including chorionic gonadotropin and substances having oestrogen, progestin, or adrenocorticoid activity. (12 Dec 1998) |
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| placental insufficiency | Failure of the placenta to deliver an adequate supply of nutrients and oxygen to the foetus. (12 Dec 1998) |
| placental lactogen | <chemical> A polypeptide hormone secreted by the placenta that enters the maternal circulation and disappears from the circulation immediately after delivery. It has growth-promoting activity, is immunologically similar to human growth hormone, and inhibits maternal insulin activity during pregnancy. By inhibiting glucose oxidation it can increase the glucose supply to a foetus developing in a malnourished mother. Chemical name: Lactogen, placental (12 Dec 1998) |
| placental lobes | Cotyledons of the human placenta, viewed on the maternal surface as irregularly shaped elevations or lobe's. (05 Mar 2000) |
| placental membrane | The semipermeable layer of foetal tissue separating the maternal from the foetal blood in the placenta; composed of: 1) endothelium of the foetal vessels in the chorionic villi, 2) stromata of the villi, 3) cytotrophoblast (negligible after the fifth month of gestation), and 4) syncytial trophoblast covering the villi; the placental membrane acts as a selective membrane regulating passage of substances from the maternal to the foetal blood. Synonym: placental barrier. (05 Mar 2000) |
| placental parasitic twin | Underdeveloped twin of allantoidangiopagous twin; joined by umbilical vessels. Synonym: placental parasitic twin. Origin: omphalo-+ G. Sitos, food (05 Mar 2000) |
| placental plasmodium | The syncytial outer layer of the trophoblast; site of synthesis of human chorionic gonadotropin. See: trophoblast. Synonym: placental plasmodium, plasmodial trophoblast, plasmodiotrophoblast, syncytial trophoblast, syntrophoblast. Origin: syncytium + trophoblast (05 Mar 2000) |
| placental polyp | A polyp developed from a piece of retained placenta. (05 Mar 2000) |
| placental presentation | <obstetrics> The anatomic positioning of the placenta over the cervical os (opening to the birth canal). This is an important cause of painless third trimester bleeding in the pregnant female. Many cases of placenta previa will require cesarean section delivery. (31 Dec 1997) |
| placental septa | Incomplete partitions between placental cotyledons; they are covered with trophoblast and contain a core of maternal tissue. (05 Mar 2000) |
| placental sign | <clinical sign> Slight endometrial oozing of blood which occurs in certain animals and sometimes in women at the time of implantation of the fertilised ovum; in women, if the blood appears externally it may be mistaken for a scanty menstrual period. (05 Mar 2000) |
| placental site trophoblastic tumour | A tumour usually arising in the uterus of parous women during reproductive years. Histologically, the tumour consists of a predominance of intermediate trophoblastic cells with fibrinoid material and vascular invasion. (05 Mar 2000) |
| placental souffle | A blowing sound, synchronous with the cardiac systole of the mother, heard on auscultation of the pregnant uterus. Synonym: placental souffle. (05 Mar 2000) |
| placental stage of labour | The part of labour from the birth of the baby until the placenta (afterbirth) and foetal membranes are delivered. Also called the third stage of labour. (12 Dec 1998) |
| placental sulfatase deficiency | <enzyme> An enzyme defect in the placenta which results in failure of conversion of 16a-hydroxydehydroepiandrosterone to estriol; women with this condition rarely enter into spontaneous labour. (05 Mar 2000) |