Urothelial hyperplasia of the urinary bladder of the rat induced by mechanical perforation and phenacetin treatment.

Mechanical perforation of the urinary bladder of Sprague-Dawley rats and subsequent administration of phenacetin in the diet induced urothelial hyperplasia in 11 of 12 rats. No pathological changes were found in the bladders of the control rats only submitted to mechanical perforation or phenacetin treatment only. The hyperplastic changes varied from mild focal urothelial hyperplasia after one week to severe focal and diffuse nodular and papillary hyperplasia after 3 weeks.