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. Author manuscript; available in PMC: 2009 Oct 1.
Published in final edited form as: Toxicol Appl Pharmacol. 2008 Jul 1;232(1):78–85. doi: 10.1016/j.taap.2008.06.007

Figure 2. Cystic papillary carcinoma in E2-treated mammary gland after 120 days treatment.

Figure 2

Female ACI rats were treated with an E2 pellet (s.c., 3 mg E2 + 17 mg cholesterol) for 120 days. The ductal structures are markedly dilated (compare with uninvolved hyperplastic lobular unit (HLU) at the top of image). The neoplastic epithelium grows into the lumen forming papillae and rigid arches devoid of fibrovascular cores. The neoplastic cells are enlarged and generally uniform in size. In addition to the hypertrophic and hyperplastic changes, E2 treatment results in the appearance of malignant lesions. The mammary tissue of one animal showed cystic papillary carcinoma (CA) following 120 days of E2 treatment.