Evaluation of different rat models intrauterine adhesion models and improvement of the technique for their establishment

Intrauterine adhesion (IUA), a leading cause of uterine infertility, is characterized by endometrial fibrosis. Implementing an appropriate animal model is essential for the research on the mechanisms of IUA. In the present study, we established and evaluated different intrauterine adhesion modeling procedures in rats to provide a reference for researchers. Rat IUA models were established by mechanical injury, 95% ethanol injection, and dual (mechanical injury with infection) injury. After two estrus cycles, the female rats were mated with sexually mature male rats, and uterine tissues were obtained on the 5th day of pregnancy. Hematoxylin and eosin staining and immunohistochemical detection of cytokeratin 19 and vimentin were performed to assess the morphology of the endometrium. Masson’s trichrome staining and the expression of transforming growth factor-β1 and collagen I were used to assess the endometrium fibrosis. The expression of integrin avβ3, leukemia inhibitory factor, and homeobox gene A10 in the rat endometrium was used to evaluate the endometrial receptivity. In addition, the efficiency of embryo implantation was examined in the uterus on the 8th day of pregnancy. Our study found that mechanical injury caused by a curette can be completely repaired after two estrus cycles. However, dual injury and 95% ethanol injection can be used to establish an IUA rat model, and the dual injury is closer to the clinicpathological characteristics of IUA.