Endometrial receptivity as studied using endometrium-derived organoids and corresponding implantation models

In reproduction, the window of implantation (WoI) is described as the narrow time frame with maximal endometrial receptivity for embryo implantation. In humans, the WoI is achieved 7–10 days after ovulation, and characterized by molecular and histological changes such as inhibition of epithelial cell proliferation and epithelial/stromal cell remodeling. Here, we will search for mechanisms and markers of receptivity using organoid and implantation models. First, we will focus on acyl-CoA synthetase long-chain family member 4 (ACSL4) which has been found to be significantly upregulated in LH+7 (receptive) endometrium (expressed by the local epithelial cells), compared to LH+2 endometrium, and significantly downregulated in repeated implantation failure (RIF) patients, indicating its potential role in endometrial receptivity.