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Table 1 Variations in the trophoblast comprising the interhemal area of the chorioallantoic placenta.

From: Comparative aspects of trophoblast development and placentation

Placental Type Trophoblast Component Examples
Hemomonochorial Syncytial trophoblast, villous Armadillo; higher primates
  Syncytial trophoblast, labyrinthine Most hystricomorph rodents (e.g. guinea pig, capybara); sciuromorph rodents (squirrels)
  Cellular trophoblast Hyraxes; spiny tenrecs (e.g Echinops); mollosid bats (late gestation); some myomorph rodents (Zapus, Jaculus)
Hemodichorial Syncytial (maternal facing) and cellular trophoblast Lagomorphs; vespertilionid bats
Hemotrichorial Cellular trophoblast (maternal facing) and two layers of syncytial trophoblast Most myomorph rodents (e.g. rat, mouse)
Endotheliochorial Syncytial trophoblast (fenestrated) Sloths; shrews (insectivores)
  Syncytial trophoblast (nonfenestrated) Carnivores and pinnipeds
  Cellular trophoblast Elephants; some sciuromorph rodents (Dipodomys, Microdipodops); some bats (Natalus, Saccopteryx)
Epitheliochorial Cellular trophoblast only Lower primates; pangolin; some artiodactyls (e.g. pig)
  Cellular trophoblast with trophoblastic girdle cells Equids (perissodactyls, e.g. horse)
Synepitheliochorial Cellular trophoblast; fusion of binucleate trophoblastic cells with uterine epithelium Ruminants (artiodactyls, e.g. sheep, cow)
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