placenta

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placenta (plă-sent-ă) n. an organ within the uterus by means of which the embryo is attached to the wall of the uterus. Its primary function is to provide the embryo with nourishment, eliminate its wastes, and exchange respiratory gases. It also functions as a gland, secreting chorionic gonadotrophin, progesterone, and oestrogens. See also afterbirth. p. praevia a condition in which the placenta is situated wholly or partially in the lower and noncontractile part of the uterus. When this becomes elongated and stretched during the last few weeks of pregnancy, and the cervix becomes stretched either before or during labour, placental separation and haemorrhage will occur. If the placenta is situated entirely before the presenting part of the fetus, delivery must be by Caesarean section.
—placental (plă-sen-t'l) adj.

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