Definition of placental in US English:



  • 1Relating to a placenta.

    • ‘None of the women with PAPP-A values in the top 60% had stillbirths caused by placental problems.’
    • ‘We applaud stem-cell research, especially with adult cells, and placental and umbilical tissues.’
    • ‘The couple, from Whinmoor, Leeds, claim greater care should have been taken of the woman who was diagnosed with pre-eclampsia - a placental defect - some weeks before the birth.’
    • ‘She believes her 14-year-old daughter's scleroderma, a systemic sclerosis, is linked to silicone crossing the placental barrier.’
    • ‘I would like to see more about the possibility of using the placental and adult stem cells vs. the embryonic ones.’
    • ‘In mice, the gender of adjacent siblings on the placental fetus line in the uterus will affect such things as the male/female ratio of a given mouse's subsequent offspring, and even the longevity of those offspring.’
    • ‘Infection of humans usually occurs by inhalation of these organisms from air that contains airborne barnyard dust contaminated by dried placental material, birth fluids, and excreta of infected herd animals.’
    1. 1.1Zoology Relating to or denoting mammals that possess a placenta; eutherian.
      • ‘The reproductive system of the therians (marsupial and placental mammals) is a complex variation on the egg-layer's basic tubular structure.’
      • ‘The quagga is a placental mammal, a group also called Eutheria by scientists.’
      • ‘Both taxa are placental or eutherian mammals, but their relationships to other eutherians continue to be a source of discussion.’
      • ‘There are several cases of convergent evolution between marsupials and placental mammals, in which the two animals have evolved to fill the same ecological niche in different parts of the world.’
      • ‘To distinguish them from the marsupials and the placental mammals the monotremes are placed in their own class, the prototheria.’


  • A placental mammal.

    • ‘It is significant because a vast majority of mammals alive today are placentals.’
    • ‘Split of therians into placentals and marsupials happens at this time.’
    • ‘An unquestioned monotreme, Steropodon has molars that are surprisingly similar to those of marsupials and placentals, suggesting a closer relationship to living therians than had generally been thought.’
    • ‘‘Looking across the world, 99.9 percent of modern mammals are placentals and marsupials, so finding how they came about is an important question,’ he said.’
    • ‘Cathy's work suggests that, unlike placentals, marsupial mammals never had to rediscover red; for them, it's always been there.’