Uterine molecular changes for non-invasive embryonic attachment in the marsupials Macropus eugenii (Macropodidae) and Trichosurus vulpecula (Phalangeridae)

Abstract

Pregnancy in mammals requires remodeling of the uterus to become receptive to the implanting embryo. Remarkably similar morphological changes to the uterine epithelium occur in both eutherian and marsupial mammals, irrespective of placental type. Nevertheless, molecular differences in uterine remodeling indicate that the marsupial uterus employs maternal defences, including molecular reinforcement of the uterine epithelium, to regulate embryonic invasion. Non-invasive (epitheliochorial) embryonic attachment in marsupials likely evolved secondarily from invasive attachment, so uterine defences in these species may prevent embryonic invasion. We tested this hypothesis by identifying localizati..