Effects of raloxifene (RAL) and Y134 on mammary gland DNA synthesis. Ovariectomized rats were treated with 17β-oestradiol (E2) in conjunction with a daily oral dose of either RAL or Y134. The upper panel shows: (a) sham-operated group given vehicle only (negative control); (b) ovariectomized rats administered vehicle only; (c) ovariectomized rats supplemented with E2 alone; (d) ovariectomized rats administered both E2 and RAL (3 mg kg−1 day−1); (e) ovariectomized rats administered both E2 and Y134 (3 mg kg−1 day−1) and (f) ovariectomized rats administered both E2 and Y134 (1 mg kg−1 day−1). The mammary glands were collected and longitudinal sections made for immunohistochemistry at autopsy. Raw data were generated in a blind manner with a minimum of five fields, and the BrdU labelling index (low panel) represents the FITC-stained vs all cells counted in each field × 1000 (magnification, × 400). SHAM, sham-operated; OVX, ovariectomized. **P<0.01 compared between OVX and E2, E2 and E2+RAL, E2 and E2+Y134, and E2+RAL and E2+Y134 (3 mg), respectively.