Figure 2.

Uterine epithelial ESR1 is indispensable for stromal cell decidualization. A, Uterine epithelial RNA was extracted from Esr1^fl/fl and WE^d/d mice on day 4 of pregnancy (n = 3–4) and analyzed by real-time PCR. Relative levels of Esr1 mRNA expression in uterine epithelium WE^d/d mice are compared with those in Esr1^fl/fl control mice. Ck18 was used as internal control to normalize gene expression. The data are represented as the mean fold induction ± SEM. ***, P < .001. B, Immunohistochemical localization of ESR1 in the uterus of Esr1^fl/fl and WE^d/d 18 hours after E treatment. Note the absence of glandular and luminal epithelial expression of ESR1 in WE^d/d uteri, whereas stromal expression remains intact. G, glandular epithelium; L, luminal epithelium; S, stroma. C, The right uterine horns (R) of Esr1^fl/fl and WE^d/d mice were stimulated, whereas the left horns (L) were left unstimulated. When examined after 72 hours, only the right horn of Esr1^fl/fl exhibited a robust decidual response after stimulation. The stimulated right horn of WE^d/d failed to show any decidual response after 72 hours. D, Ratio of wet weight gains of right and left horns. **, P ≤ .01 (t test, n = 5).