Glover LE, et al. - This study entailed characterization of natural killer (NK) cell profiles in endometriosis that may predict embryo implantation, given altered uterine natural killer (uNK) cell development in endometriosis-associated infertility. Among patients with endometriosis who proceeded to successful or failed embryo implantation, marked differences were apparent in uterine NK progenitor cell populations, which, additionally, may define a novel predictor of implantation success. Furthermore, the fundamental differences inherent in NK cell repertoires between blood and uterine compartments were also underlined in the findings.