Meeting Abstract
Successful mammalian pregnancy requires remodeling of the uterus to become receptive to embryonic attachment. Remarkably similar morphological changes to the inner uterine epithelium occur in both eutherian (placental) mammals and marsupials. Yet molecular differences in marsupial pregnancy, particularly molecular reinforcement of the uterine epithelium just before embryonic invasion in the marsupial Sminthopsis crassicaudata (Dasyuridae), suggest that marsupial pregnancy may involve maternal defenses to regulate invasion and tissue destruction by the embryo. To test this theory, we identified patterns of fluorescence of a key basal molecule (talin), which anchors cells of the epithelium to the underlying tissue, during pregnancy in the tammar wallaby (Macropus eugenii; Macropodidae). Implantation is non-invasive in M. eugenii, yet talin undergoes a clear distributional change during pregnancy, including recruitment to the base of the epithelium just before attachment, that closely resembles that of invasive implantation in S. crassicaudata. We conclude that less invasive, and non-invasive, implantation in marsupials may have evolved via accumulation of maternal defenses, as reinforcement of the epithelium before embryonic attachment occurs in marsupial species with different modes of implantation. Hence recruitment of basal molecules to the epithelium, particularly talin, may have played a key role in this evolutionary transition.
