Apposition to endometrial epithelial cells activates mouse blastocysts for implantation

This study used an establishedin vitro model of implantation to examine cellular and molecular interactions during blastocyst attachment to endometrial epithelial cells.PARTICIPANTS/MATERIALS, SETTING, METHODSMouse blastocysts developed from embryonic day (E) 1.5in vitro were hatched and co-cultured with confluent human endometrial adenocarcinoma-derived Ishikawa cells in serum-free medium. A scale of attachment stability based on blastocyst oscillation upon agitation was devised. Blastocysts were monitored for 48 h to establish the kinetics of implantation, and optical sectioning using fluorescence microscopy revealed attachment and invasion interfaces. Quantitative PCR was used to determine blastocyst gene expression. Data from a total of 680 mouse blastocysts are reported, with 3 –6 experimental replicates.T-test and ANOVA analyses established statistical significance atP< 0.05,P< 0.01 andP< 0.001.MAIN RESULTS AND THE ROLE OF CHANCEHatched E4.5 mouse blastocysts exhibited weak attachment to confluent Ishikawa cells over the first 24 h of co-culture, with intermediate and stable attachment occurring from 28 h (E5.5 + 4 h) in a hormone-independent manner. Attached embryos fixed after 48 h (E6.5) frequently exhibited outgrowths, characterised morphologically and with antibody markers as trophoblast giant cells (TGCs), which had breached the Ishikawa cell layer. Beginning co-culture at E5.5 also resulted in intermediate and stable attachment from E5.5 + 4 h; however...
Source: Molecular Human Reproduction - Category: Molecular Biology Source Type: research