Iron metabolism and the role of macrophages in the pelvic cavity in endometriosispathology are graphically postulated in Fig. 3.Activated macrophages recruited inside the pelvic cavity are deeply engaged in degradationof erythrocytes, as indicated by numerous iron-loaded macrophages in the peritoneal fluidfrom both endometriosis patients and mice intraperitoneally injected with erythrocytes.Macrophages typically phagocytose senescent erythrocytes or endocytose the Hb–Hp complex. Here, GSTM1 is linked to endometriosis.