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) |