Estrogen receptor a is required for oviductal transport of embryos

Newly fertilized embryos spend the first few days within the oviduct and are transported to the uterus, where they implant onto the uterine wall.An implantation of the embryo before reaching the uterus could result in ectopic pregnancy and lead tomaternaldeath. Estrogen is necessary for embryo transport inmammals;however, the mechanism involved in estrogen-mediated cellular function within the oviduct remains unclear. In this study, we showinmouse models that ciliary length and beat frequency of the oviductal epithelial cells are regulated through estrogen receptor a (ESR1) but not estrogen receptor β (ESR2).Gene profiling indicated that transcripts in theWNT/ β-catenin (WNT/CTNNB1) signaling pathway were regulated by estrogen in mouse oviduct, and inhibition of this pathway in a whole oviduct culture system resulted in a decreased embryo transport distance. However, selective ablation of CTNNB1 from the oviductal ciliated cells did not affect embryo transport, possibly because of a compensatorymechanismvia intactCTNNB1inthe adjacent secretory cells. In summary,wedemonstrated that disruption of estrogen signaling in oviductal epithelial cells alters ciliary function and impairs embryo transport. Therefore, our findings may provide a better understanding of etiology of the ectopic pregnancy that is associated with alteration of estrogen signals.