(a) In situ hybridization of Ptgs2 in uteri on day 5 of pregnancy. The expression patterns of Ptgs2 critical for implantation show no significant difference in WT and Cnr1-/-Cnr2-/- females. CK8 staining outlines uterine epithelial cells. (b) In situ hybridization of Bmp2 in uteri on day 5 of pregnancy. Decidual responses in Cnr1-/-Cnr2-/- females are much weaker than those in WT females. le, luminal epithelium; s, stroma; ge, glandular epithelium; Asterisks, positions of embryos; Scale bars, 500 μm. All images are representative of three independent experiments.