Whole-mount (A), H&E (B), and immunohistochemical (C, D) staining of mammary glands from Brca1S1152A/S1152A and wild-type mice at 18 months of age. The boxed areas are amplified and displayed on the right. Immunohistochemical imaging was achieved using primary antibodies against cyclin D1 (C) and phospho-ER-α (D). Bars, 100 μm. WT, wild-type; S1152A, Brca1S1152A/S1152A.