Fig. 2. Inactivation of Wnt-β-catenin signaling derails on-time implantation.

(A) Implantation in mice receiving empty or DKK1 ADV on days 5 and 6 of pregnancy. Implantation sites (IS) were visualized by the blue dye method. Numbers within the bar indicate the number of mice with IS/total number of mice examined. (B, C) Representative photomicrograph of uteri with or without IS (blue bands) and recovered unimplanted morphologically normal blastocysts from those without blue reaction (Bar, 50 μm). (D) Implantation in mice receiving vehicle, PKF115-584 or CGP049090 (each 10 mg/Kg·BW) on day 5. Numbers within the bar indicate the number of mice with IS/total number of mice examined. (E) In situ hybridization showing comparable expressions of amphiregulin (AR) and Hoxa-10 in day 4 uteri of mice receiving empty or DKK1 ADV (Bar, 200 μm). (F-I) Overexpression of DKK1 via DKK1 ADV exerts no effects on the cellular level of total β-catenin, but remarkably attenuates nuclear stabilization of active dephospho β-catenin and c-Myc expression in blastocyst trophectoderms (Tr) when examined on day 4 midnight (day 4.5). In contrast, Nanog, an inner cell mass (ICM) marker gene, is normally expressed in ICM cells of blastocysts recovered from pregnant females receiving either DKK1 ADV or empty vectors on day 4.5. Represented immunofluorescence staining images depict Cy3-labeled antigens as red, SYTO-13-labeled nuclei as green and merge as yellow. Bar, 50 μm.