Species differences in regenerative hyperplasia of bladder urothelium after transurethral cauterization.

The early histological changes in bladder urothelium following transurethral cauterization were sequentially studied in female rats, mice, hamsters and guinea pigs. The changes differed markedly between species: papillary hyperplasia or papilloma in the rats and simple hyperplasia in the mice, hamsters and guinea pigs. The regenerative response to the fulgurative ulcer within a given species was similar to the early response previously observed by others following administration of known bladder carcinogens. This suggests that there may be a regulatory mechanism in the urothelium which is common to urothelial proliferations induced by both carcinogenic and non-carcinogenic stimulations, though differing between animal species.