TEMPORAL AND SPATIAL FACTORS IN DIETHYLSTILBESTROL-INDUCED SQUAMOUS METAPLASIA IN THE DEVELOPING HUMAN PROSTATE .2. PERSISTENT CHANGES AFTER REMOVAL OF DIETHYLSTILBESTROL

To determine if the metaplastic effects of diethylstilbestrol (DES) on prostatic development are reversible, human fetal prostates (obtained from abortus specimens 6-22 weeks old) were bisected mid-sagittally; one half was grafted under the renal capsule of untreated, athymic, ma le nude mice and the contralateral half was similarly grafted into DES -treated hosts. Severe squamous metaplasia seen in the prostatic ducts after 1 month of continuous DES exposure either disappeared entirely or became reduced in extent and degree after retransplantation of the DES-treated specimens to untreated, intact male hosts and 2 additional months of growth. However, 14 of 21 DES-treated prostates harvested a fter a 2-month recovery period without DES revealed ductal dilatation (ectasia) and persistent distortion of ductal architecture. Ectasia wa s most severe in the proximal ducts near the urethra and in prostates 17 weeks or older at the end of 1 month of DES treatment. The clinical consequences of early alteration of prostatic ductal architecture and development are potentially deleterious, as men who were prenatally e xposed to DES may be at increased risk for the development of prostati c disease.