IDO1 and endometriosis: The in vivo results from this study showed that 1-MT, a specific inhibitor of IDO1, can notably improve the condition of endometriosis, as similar as ER inhibitor, which provide evidences that blocking IDO1 in ectopic lesions may be a novel treatment option for endometriosis, not only by virtue of its effects on biological activities of ESCs, but also on local immune-tolerance environment effected by inhibition of the differentiation and functions of Treg cells.