Menstrual endometrial supernatant may induce stromal endometriosis in baboons.

We tested the hypothesis that endometriosis can be induced in baboons more successfully by intra-pelvic injection of the pellet of menstrual endometrium when compared to its supernatant. Menstrual endometrium, separated into pellet (n = 5) and supernatant fractions ( n = 8), or phosphate buffered saline (1 ml, n = 7, controls) was injected laparoscopically into the pelvis. During laparoscopy 25 days later, the number (ρ = 0.027) and surface area (ρ <0.0001) of endometriosis-like lesions were significantly higher in the pellet group, than in the supernatant group, or in the control group. Histological typical endometriosis was present only in the endometrial pellet group (1/15), whereas stromal endometriosis was observed in both the pellet group (6/15), and the supernatant group (6/20). Peritoneal endometrial like glands were observed in both the endometrial pellet group (3/15), and in the supernatant group (1/20). In conclusion, we confirmed our hypothesis that endometriosis can be induced in baboons more successfully by intrapelvic injection of the pellet of menstrual endometrium when compared to its supernatant.