Female sprague dawley rats

Female Sprague-Dawley rats, at 10 weeks of age, were purchased from HFK Bioscience Co. (Beijing, China). The rats were housed in SPF (specific pathogen-free) lab (SYXK 2017-0004, China) in an environment with a temperature of 22 ± 1 °C, relative humidity of 50 ± 1%, and a light/dark cycle of 12/12 h. Sterilized food and water were available ad libitum. All animal studies (including the euthanasia procedure) were done in compliance with the regulations and guidelines of China Medical University institutional animal care and conducted according to the AAALAC and the IACUC guidelines.
After a week to achieve regular estrous cyclicity determined by vaginal smearing, the rats were anesthetized by 1 ml/kg 3% sodium pentobarbital i.p. on diestrus. Then, a vertical incision (~ 20 mm) was preformed longitudinally, followed by the insertion and rotation of a 16-gauge needle to scratch the entire inner endometrial surface of both laterals, until the uterine walls became rough and pale, leaving the uterine serosa intact. The uterus was subsequently washed with sterile normal saline. Finally, the uterine and abdominal wounds were closed.

Female Sprague Dawley rats (200–230 g) and female BALB/c nude mice (6–8 weeks, 18–20 g) were purchased from Beijing Huafukang Biotechnology Co., Ltd. (Beijing, China). All animal experiments were performed in compliance with the Guide for the Care and Use of Laboratory Animals and approved by the Animal Care Welfare Committee of Guizhou Medical University (NO. 2000674).