Endometriosis (EM) as a common and intractable gynecological disease is characterized by unknown etiology and complex pathologic changes. Many factors of the disease are uncertain at the molecular level and it is difficult to study clinically. In this study, we attempted to establish a nude mice model of EM for dynamical observation of the genesis and development of the disease, morphological changes in tissue, and biological behaviors. METHODS Tissue processing The endometrium of late secretory phase was obtained from 24 patients with endometriosis and 24 normal premenopausal women undergoing endometrial biopsy or hysterectomy. Some fresh endometrial tissues were kept at -70℃, and others were washed in phosphate buffer solution (PBS) and cut into 2-3 mm3 fragments under sterile conditions. The tissues were transported in a mixture of PBS, 200 U/ml penicillin, and 200 μg/ml streptomycin. The specimens of the human greater omentum were obtained from patients with benign gynecologic diseases, and processed as the endometrial tissues. All the above tissues were proved normal pathologically after operation. Endometriosis (EM) as a common and intractable gynecological disease is characterized by unknown etiology and complex pathologic changes. Many factors of the disease are uncertain at the molecular level and it is difficult to study clinically. In this study, we attempted to establish a nude mice model of EM for dynamical observation of the genesis and development of the disease, morphological changes in tissue, and biological behaviors. METHODS Tissue processing The endometrium of late secretory phase was obtained from 24 patients with endometriosis and 24 normal premenopausal women undergoing endometrial biopsy or hysterectomy. Some fresh endometrial tissues were kept at -70 ° C, and others were washed in phosphate buffer solution (PBS) and cut into 2-3 mm3 fractions under sterile conditions. The tissues were transported in a mixture of PBS, 200 U / ml penicillin, and 200 μg / ml streptomycin. The specimens of the human greater omentum were obtained from patients with benign gynecologi c diseases, and processed as the endometrial tissues. All the said tissues were verified normal pathologically after operation.