Induction of Endometriosis by implantation of endometrial fragments in female rats

Background: Endometriosis is defined as the growth of endometrial tissues in ectopic places outside the uterus. This disease has an important effect on the health and fertility of affected women. It's etiology is not clearly known. For better understanding the pathophysiology of this disease, many researchers study on several aspects of the disease on animals. Objective: In this experimental study endometriosis was induced in female rats surgically and then its side effects were investigated with special focus on adhesion formation that is a major problem in women with this disease. Materials and methods: In Protestrous phase, female rats were randomly divided into two groups. In both groups, under intra peritoneal anesthesia, laparotomy was done and left horn and associated fat were removed. In experimented group (A), the removed endometrium was cut to six square pieces (2mm each) and they were sutured to the peritoneum, near ovaries and subcutaneous. In sham group (B), the same procedure was done for the fat tissues around the removed horn and the pieces were sutured to the same places. After 8 weeks, in Protestrous phase, clinical adhesion and size of implants were evaluated. Results: The total mean size of implants was calculated in each group, and this was significantly larger in experimented group (25.4 mm versus 2 mm p=0.000). The mean diameter of implants that calculated for each site of implantation in experimented group were significantly larger in left peritoneum (p=0.002), followed by right (p=0.000) and left (p=0.000) ovaries. The endometrial tissues grew in 100% of implants in subcutaneous area. Clinical adhesions (Score ≥ 2) were detected in 7 out of 10 in experimented group and in 2 out 10 in control group. The number of Esterous cycle were similar in both groups. Conclusion: Our study showed that after inducing endometriosis by surgical approach, only endometrial implants grew as a cystic structures and this is a unique aspect of endometrial cells. Our results showed that endometriosis had a direct effect on adhesion formation, not surgery alone and induction of this disease didn't have any adverse effect on ovarian function in female rats.