Surgical xenografts of subcutaneous endometriosis in mice: A possible useful animal modd for the study of endumetriosis

Objective Thirty mature female ICR mice were used in order to develop an animal model of subcutaneous endometriosis. Methods Experimental endometriosis was produced by autotiansplantation of uterine fragments to subcutaneous region of the abdomen and to the peritoneum. A second laparotomy was performed 3 weeks later to measure the size of the grafts, and bilateral ovariectomies (OVX) were performed at the same time. A third laparotomy was performed 4 weeks after OVX.The mice were then randomly divided into two groups and injected with either 17B- estradiol (E2, 0.5μg/mouse in 0.1ml sesame oil) every 3 days for 3 weeks or with the vehicle only as a control.The change of volume of the subcutaneous explants was compared with that of the peritoneal explants after OVX and again after E2 administration. Results The rate of successful transplantation of the subcutaneous endometrial explants was 73.3% (22/30), which was similar to that of the peritoneal endometrial explants (86.7%; 26/30) .Both subcutaneous and peritoneal explants showed similar patterns of volume decrease after OVX (γ = 0.783, P 0.001) and volume increase after E2 treatment (7 = 0.748, P = 0.01) .The mean weight of the subcutaneous explants was sig-nificantly greater in E2-treated OVX mice (30.2±4.7mg, n= 10) than that in oil - treated OVX mice (15.4±3.9mg, n =10,P0.05). Conclusions These results suggest that experimental endometriosis can be successfully induced in subcutaneous tissues in mice.The subcutaneous explants were identical to the peritoneal explants in both their histological characteristics and biological responsiveness to ovarian hormones and could be easily measured from the outside without repeated operation.