page_title: Placenta
section_title: Clinical significance
hierarchical_section_title: Placenta / Clinical significance
caption_attribution_description: English: Micrograph of cytomegalovirus (CMV) placentitis. H&amp;E stain. CMV is a TORCH infection. Compared to chorioamnionitis, TORCH infection are fairly uncommon. They may result in an abortion (miscarriage). The villi in the image have marked inflammation that is predominately lymphocytic. A characteristic CMV cell is seen right of centre in the image. The red blood cells surrounding the chorionic villi are maternal. Related images Field #1. Close-up of Field #1 - shows the characteristic nucleus Field #2. Close-up of Field #2 - shows the characteristic nucleus
context_page_description: The placenta is a temporary organ that connects the developing fetus via the umbilical cord to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, and gas exchange via the mother's blood supply; to fight against internal infection; and to produce hormones which support pregnancy. Placentas are a defining characteristic of placental mammals, but are also found in marsupials and some non-mammals with varying levels of development.
  The placenta functions as a fetomaternal organ with two components: the fetal placenta, which develops from the same blastocyst that forms the fetus, and the maternal placenta, which develops from the maternal uterine tissue. It metabolizes a number of substances and can release metabolic products into maternal or fetal circulations. The placenta is expelled from the body upon birth of the fetus.
  Placentas probably first evolved about 150 million to 200 million years ago.
context_section_description: Numerous pathologies can affect the placenta.
  Placenta accreta, when the placenta implants too deeply, all the way to the actual muscle of uterine wall (without penetrating it)
  Placenta praevia, when the placement of the placenta is too close to or blocks the cervix
  Placental abruption/abruptio placentae, premature detachment of the placenta
  Infections involving the placenta:
  Placentitis, such as the TORCH infections.
  Chorioamnionitis.
caption: Micrograph of a cytomegalovirus (CMV) infection of the placenta (CMV placentitis). The characteristic large nucleus of a CMV-infected cell is seen off-centre at the bottom-right of the image. H&E stain.
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