Abstract: Objective：Injecting different concentrations of human eutopic and ectopic endometrial cells into the abdominal subcutaneous tissue in nude mice. The formation of ectopic lesions was observed and compared, in order to establish a visible endometriosis model (EMs) that was non-invasively, continuously and dynamically. Methods：Twenty human eutopic endometrial samples and ovarian endometriosis cyst walls were obtained, endometrial cells were digested and cultured respectively. Three different concentrations of 2.5×106/200 μL, 5×106/200 μL and 1×10７/200 μL were injected respectively into the abdominal subcutaneous tissue of nude mice. The time when lesions began to appear were observed and recorded. The incidence and volume of lesions on the 5th day, 10th day and 15th day after injection was calculated. On the 15th day after injection, the visible lesions were removed and identified by histologic and immunohistochemical examination. Comfirm the best cells, the optimal concentration of cells and the suitable time to observe the lesions through comparation. Results：Visible lesions could be successfully induced by injecting human eutopic and ectopic endometrial cells. Pathological analysis of lesions showed that glandular structures were surrounded by dense stromal cells. Immunohistochemical examination results confirmed that the lesions were formed by human endometrial cells. There were no statistically significant differences among the groups on the time when a lesion occurred (F=0.230, P=0.942). The optimal concentration of injected cells was 5×106/200 μL, the best time to establish the model was on the 10th day after injection. Under these conditions, the incidence of lesions on the 10th day was 100% in the ectopic cells group and 75% in the eutopic cells group, the difference was statistically significant ( χ2=9.143, P=0.002). Conclusions：The ectopic endometrial cells were more suitable for establishing a visible EMs model compared with the eutopic endometrial cells. Co-cultured ectopic endometrial cells of 5×106/200 μL concentration were injected in the abdominal subcutaneous of nude mice could successfully establish the visible EMs model on the 10th day and the incidence could up to 100%. The lesions could be observed non-invasively, continuously and dynamically. It was an ideal model to study the abdominal wall EMs.

Key words: Endometriosis, Abdominal wall endometriosis, Endometrium, Visible model, Disease models, animal, Mice, nude