placenta

noun

pla·cen·ta | \ plə-ˈsen-tə

plural placentas or placentae\ plə-ˈsen-(ˌ)tē

Definition of placenta

1 : the vascular organ in mammals except monotremes and marsupials that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues also : an analogous organ in another animal

2 : a sporangium-bearing surface especially : the part of the carpel bearing ovules

Examples of placenta in a Sentence

Recent Examples on the Web

One still had a placenta and umbilical cord attached. — Lauren Fox, BostonGlobe.com, "Mother in Blackstone ‘house of horrors’ case sentenced to 6 to 8 years in prison," 11 July 2019 After that, staffers look for the placenta to pass and for nursing behaviors to begin. — Steve Johnson, chicagotribune.com, "Shedd Aquarium beluga gives birth to healthy calf," 4 July 2019 Just as frightening is this: T. cruzi can cross the placenta. — Marc Burckhardt, National Geographic, "A little-known parasite infects 300,000 people in the U.S.," 17 June 2019 Twin-to-Twin Transfusion Syndrome, or TTTS, according to Johns Hopkins Medicine, is a rare condition that occurs in pregnancies when twins share one placenta and a network of blood vessels. — Matt Kawahara, SFChronicle.com, "Fatherhood drives Raiders rookie safety Johnathan Abram," 16 June 2019 The animal rights group said the video also shows cows being milked just hours after giving birth, with the placenta sacks still visible and blood coating their legs. — Washington Post, "New video shows adult cows being abused at Indiana farm," 12 June 2019 For example, fetal mammals have a special hemoglobin in their blood with extra affinity for oxygen, which helps them to draw oxygen out of the maternal blood supply in the placenta. — Quanta Magazine, "Icefish Study Adds Another Color to the Story of Blood," 22 Apr. 2019 One still had a placenta and umbilical cord attached. — Lauren Fox, BostonGlobe.com, "Erika Murray found not guilty of murder in Blackstone ‘house of horrors’ case," 20 June 2019 Our mammalian ancestors coopted that gene, now known as syncytin, for a new purpose: to help form the placenta, the connection between mother and fetus. — Quanta Magazine, "Killer Virus Is Invading Koala DNA," 4 Mar. 2015

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'placenta.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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16 Jul 2019

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The first known use of placenta was in 1638

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More Definitions for placenta

placenta

noun

English Language Learners Definition of placenta

medical : the organ in mammals that forms inside the mother's uterus, nourishes the unborn baby, and is pushed out of the mother after the birth of the baby

See the full definition for placenta in the English Language Learners Dictionary

placenta

noun

pla·cen·ta | \ plə-ˈsen-tə

Kids Definition of placenta

: the organ in most mammals by which the fetus is joined to the uterus of the mother and is nourished

placenta

noun

pla·cen·ta | \ plə-ˈsent-ə

plural placentas or placentae\ -ˈsent-(ˌ)ē

Medical Definition of placenta

: the vascular organ in mammals except monotremes and marsupials that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues permitting exchange of material by diffusion between the maternal and fetal vascular systems but without direct contact between maternal and fetal blood and typically involving the interlocking of fingerlike vascular chorionic villi with corresponding modified areas of the uterine mucosa — see abruptio placentae