A and B represent different stages of establishing homologous endometriosis model in rats. A) After transplantation of autologous uterus fragments to the inner surface of the abdominal wall. B) The transplanted fragment developed into ovoid, fluid-filled cystic lesion. Adapted with permission.[45] Copyright 2012, Elsevier. C) Homologous mouse model of endometriosis. To induce endometriotic cyst, a left uterine horn was removed from a C57 mouse, and separated endometrium tissue was sutured to the peritoneal wall. Adapted with permission.[103] Copyright 2017, Elsevier. D-H) Heterologous mouse model of endometriosis. D) SCID mouse bearing subcutaneous grafts of endometriotic tissue collected from rhesus macaques with advanced endometriosis. E-H) Images showing immunohistochemical staining (brown color) for E) ESR1, F) PGR, G) KI-67, and H) Factor 8 in endometriotic grafts collected from these mice. “s” indicates stroma and “gl” indicates glands. Adapted with permission.[11] Copyright 2020, Wiley-VCH.