(A) Levels of GPR54 mRNA expression in the uterus during early pregnancy via quantitative PCR analysis. (B) Immunostaining of GPR54 protein in mouse uterus on days 1, 4, 5, 6, 7, and 8 of pregnancy. Upper and middle panel show original magnification ×100. Sections in middle panel were magnified in the bottom with higher magnification of ×200, respectively. All experiments were repeated three times. Data are shown as means ± SEM. **p<0.01 compared with D1 of pregnancy. Scale bar, 50 µm. Con, control: without primary antibody; IS, implantation site; Int IS, inter-implantation site; em, embryo; ge, glandular epithelium; le, luminal epithelium; de, deciduas.