Abstract
BackgroundThe evolution of invasive placentation in the stem lineage of eutherian mammals entailed resolution of the incompatibility between a semi-allogenic fetus and the maternal immune system. The haemochorial placenta of nine-banded armadillo (Dasypus novemcinctus) is thought to conceal itself from the maternal immune system to some degree by developing inside a preformed blood sinus, with minimal contact with the uterine connective tissue. In the present study, we elucidate the micro-anatomical relationship between fetal and maternal tissue of the nine-banded armadillo using histochemical and immunohistochemical tools.ResultsWe conclude that the chorio-allantoic villi are separated from the myometrium by a vascular endothelial layer, as previously proposed. However, we also observe that the trophoblast cells establish direct contact with the endometrial stroma on the luminal side of the endometrium by partially replacing the endothelial lining of the sinus. Further, we demonstrate the presence of leukocytes, perhaps entrapped, in the placental fibrinoids at the interface between the intervillous space and the endometrial arcade.ConclusionsThe trophoblast of the armadillo invades the uterine tissue to a greater extent than was previously believed. We discuss the implications of this finding for the fetal-maternal immune tolerance.
Highlights
The evolution of invasive placentation in the stem lineage of eutherian mammals entailed resolution of the incompatibility between a semi-allogenic fetus and the maternal immune system
About half of the genes expressed by the fetus are of paternal origin, and are potential alloantigens for the maternal immune system [5]
Evolution of invasive placentation in eutherian stem lineage necessitated the evolution of mechanisms to control inflammation [6], and to allow for the intrauterine growth of the fetus without undergoing rejection by the maternal immune system
Summary
The evolution of invasive placentation in the stem lineage of eutherian mammals entailed resolution of the incompatibility between a semi-allogenic fetus and the maternal immune system. The haemochorial placenta of nine-banded armadillo (Dasypus novemcinctus) is thought to conceal itself from the maternal immune system to some degree by developing inside a preformed blood sinus, with minimal contact with the uterine connective tissue. The other two types of placentation are invasive, meaning that the fetal chorion is in a Invasive placentation evolved in the stem lineage of eutherian mammals ( known as placental mammals) [2,3,4]. Evolution of invasive placentation in eutherian stem lineage necessitated the evolution of mechanisms to control inflammation [6], and to allow for the intrauterine growth of the fetus without undergoing rejection by the maternal immune system. Immunology at the fetalmaternal interface is an area of active research, and numerous mechanisms of immune tolerance have been discovered in mouse and human (reviewed in [7])
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
