Effect of tamoxifen on ovarian reserve: A randomized controlled assessor-blind trial in a mouse model

To determine whether tamoxifen (TMX) exposure causes a permanent decrease in ovarian reserve. A randomized controlled assessor-blind trial including 30 adult female inbred BALB/C mice. Fifteen mice in the TMX group were given a single 0.1-mg dose of TMX intraperitoneally. Fifteen mice in the control group were given a single dose of the vehicle at the same volume intraperitoneally. Two cycles later, blood samples were collected for determination of anti-Müllerian hormone (AMH) levels, and the mice were sacrificed. After gonadectomy, ovarian size was measured, and follicles were counted under light microscopy. Median serum AMH levels were 6.53 and 6.14 ng/ml in the control and TMX groups, respectively (p=0.03). Ovarian size was significantly decreased in the TMX group. While the number of primordial (9 vs 8), primary (6 vs 3), and secondary (4.5 vs 5) follicles were similar, there were significantly fewer preantral (11.5 vs 6, p