HLA-G and endometriosis: HLA-G has been detected on eutopic endometrial cells and peritoneal fluid cells in the menstrual phase of women with or without endometriosis (Kawashima et al. 2009); however, Barrier et al. (2006) found HLA-G protein and mRNA expression only in ectopic endometrial tissue but not in eutopic endometrium in women with or without endometriosis, independently of cycle stage.