Effect of chemopreventive agents on the histology of the mammary gland
While scoring the immunohistochemical slides, we noticed that the mammary histology appeared to be altered in rats treated with chemopreventive agents. Hematoxylin and eosin stained sections from the samples after 6 weeks of treatment were analyzed by a veterinary pathologist (MAE). The mammary glands from tamoxifen-treated rats were less developed than those of untreated control animals, having fewer tertiary ducts and terminal end-buds, and could consistently be identified from a blind data set (Fig. 4). By 12 weeks of treatment, all three chemopreventive agents had a significant effect on glandular histology, with tamoxifen and 9cRA showing the greatest suppression of ductal development and lobule formation, and 4-HPR showing a relatively mild effect.