Uterine secretome initiates growth of gynecologic tissues in ectopic locations

Endosalpingiosis (ES) and endometriosis (EM) refer to the growth of tubal and endometrial epithelium respectively, outside of their site of origin. We hypothesize that uterine secretome factors drive ectopic growth. To test this, we developed a mouse model of ES and EM using tdTomato (tdT) transgenic fluorescent mice as donors. To block implantation factors, progesterone knockout (PKO) tdT mice were created. Post-ovulatory endometrium was induced hormonally in donor tdT and wild-type (WT) female mice. tdT oviductal cells and WT endometrium were harvested for intraperitoneal injection into synchronized recipient WT mice. Ectopic lesions were identified using fluorescence in-vivo imaging and then harvested for histological evaluation. Fluorescent lesions were present after oviduct implantation with and without WT endometrium. Implantation was increased (p<0.05) when tdt oviductal tissue was implanted with endometrium compared to oviductal tissue alone. Implantation was reduced (p<0.0005) in animals implanted with minced tdT oviductal tissue with PKO tdT endometrium compared to WT endometrium. In conclusion, endometrial derived implantation factors are necessary to initiate ectopic tissue growth. We have developed an animal model of ectopic growth of gynecologic tissues in a WT mouse which will potentially allow for development of new prevention and treatment modalities. ### Competing Interest Statement The authors have declared no competing interest.