title: The adherens junction is lost during normal pregnancy but not during ovarian hyperstimulated pregnancy.
abstract: During early pregnancy in the rat, the luminal uterine epithelial cells (UECs) must transform to a receptive state to permit blastocyst attachment and implantation. The implantation process involves penetration of the epithelial barrier, so it is expected that the transformation of UECs includes alterations in the lateral junctional complex. Previous studies have demonstrated a deepening of the tight junction (zonula occludens) and a reduction in the number of desmosomes (macula adherens) in UECs at the time of implantation. However, the adherens junction (zonula adherens), which is primarily responsible for cell-cell adhesion, has been little studied during early pregnancy. This study investigated the adherens junction in rat UECs during the early stages of normal pregnancy and ovarian hyperstimulated (OH) pregnancy using transmission electron microscopy. The adherens junction is present in UECs at the time of fertilisation, but is lost at the time of blastocyst implantation during normal pregnancy. Interestingly, at the time of implantation after OH, adherens junctions are retained and may impede blastocyst penetration of the epithelium. The adherens junction anchors the actin-based terminal web, which is known to be disrupted in UECs during early pregnancy. However, artificial disruption of the terminal web, using cytochalasin D, did not cause removal of the adherens junction in UECs. This study revealed that adherens junction disassembly occurs during early pregnancy, but that this process does not occur during OH pregnancy. Such disassembly does not appear to depend on the disruption of the terminal web.
authors.affiliation: Cell & Reproductive Biology Laboratory, School of Medical Sciences (Discipline of Anatomy & Histology) and The Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia. Electronic address: sdowland@anatomy.usyd.edu.au.
authors.forename: Samson N
authors.initials: SN
authors.lastname: Dowland
authors.affiliation: Cell & Reproductive Biology Laboratory, School of Medical Sciences (Discipline of Anatomy & Histology) and The Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Romanthi J
authors.initials: RJ
authors.lastname: Madawala
authors.affiliation: Cell & Reproductive Biology Laboratory, School of Medical Sciences (Discipline of Anatomy & Histology) and The Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Lindsay
authors.affiliation: Cell & Reproductive Biology Laboratory, School of Medical Sciences (Discipline of Anatomy & Histology) and The Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Murphy
mesh_terms: D022005:Adherens Junctions / Q000378:metabolism / Q000648:ultrastructure*; D000818:Animals; D003599:Cytoskeleton / Q000648:ultrastructure; D010064:Embryo Implantation; D004847:Epithelial Cells / Q000648:ultrastructure; D005260:Female; D010062:Ovulation Induction; D011247:Pregnancy; D017208:Rats, Wistar; D014599:Uterus / Q000648:ultrastructure
keywords: Adherens junction; Epithelium; Implantation; Ovarian hyperstimulation; Pregnancy; Uterine receptivity