Effects of tamoxifen on proliferation of mammary and cervical epithelium. (a) upper panels: Whole mount mammary gland micrographs from control (Ctl) and tamoxifen-treated (Tam) rats showing loss of alveoli with tamoxifen treatment 40× magnification. (a) lower panel: Graph depicting percentage of rats in each group with dominant ductal, mixed or alveolar mammary gland morphology. (b) upper panels: Bromodeoxyuridine (BrdU) positive proliferating cells detected by immunohistochemistry. Arrow shows brown staining BrdU-positive cell. 400× magnification. (b) lower panel: Quantitation of proliferating mammary epithelial cells in control (n = 12) and tamoxifen (n = 12) treated rats, *p < 0.001. (c) Cervical histology of control and tamoxifen-treated rats. Arrow shows thick stratum germinativum layer in tamoxifen-treated rats consistent with hormone stimulation.