title: No implantation in an extra-uterine pregnancy of a placentotrophic reptile.
abstract: Placentation is a common feature of live-bearing reptiles and mammals. Placentae are variable between species and can be classified by the extent that embryonic tissue breaches (invades) the uterus. Non-invasive placentation in eutherians is maternally imposed as extra-uterine embryos of species with epitheliochorial placentation will readily invade non-uterine tissues. This study documents the first observation of an extra-uterine pregnancy in a reptile; Pseudemoia entrecasteauxii, which in-utero exhibits non-invasive epitheliochorial placentation. The extra-uterine embryo did not invade maternal tissue suggesting fundamental differences between the nature and evolution of placentation in P. entrecasteauxii and eutherian mammals.
authors.affiliation: School of Biological Sciences, Heydon Laurence Building A08, University of Sydney, NSW 2006, Australia. ogri8521@uni.sydney.edu.au
authors.forename: O W
authors.initials: OW
authors.lastname: Griffith
authors.forename: J U
authors.initials: JU
authors.lastname: Van Dyke
authors.forename: M B
authors.initials: MB
authors.lastname: Thompson
mesh_terms: D000818:Animals; D005075:Biological Evolution; D010064:Embryo Implantation; D005260:Female; D008116:Lizards / Q000196:embryology* / Q000502:physiology*; D010929:Placentation; D011247:Pregnancy; D014599:Uterus / Q000502:physiology