Hyperplastic and metaplastic lesions in the reproductive tract of male rats induced by neonatal treatment with diethylstilbestrol.

Newborn male Wistar rats were castrated on the day of birth (= day 1) and treated daily with diethylstilbestrol (DES) from days 1 to 30; 1 microgram for the first 10 days of life, 2 microgram for the next 10 days and 4 microgram for the last 10 days. The animals were autopsied at 30, 90 and 270 days of age. The epithelium of the coagulating glands (CGs) and ejaculatory ducts (EDs) underwent metaplastic transformation in all DES-treated rats. These pathological changes were more marked with age. The most striking changes were found in the periurethral regions of the CGs and EDs and associated regions of the dorsal urethral wall. The normal transitional epithelial lining almost disappeared and large papillary epithelial outgrowths occurred near the opening of the EDs and CGs. This type of neoplastic change was most marked in the group of rats sacrificed at 9 months of age.