Induction of transitional cell carcinoma of the urinary bladder in rats by feeding N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide. Histological and ultrastructural findings.

After feeding with 0.188% N-[4-(5-nitro-2 furyl)-2-thiazolyl] formamide (FANFT), transitional cell carcinoma of the urinary bladder was induced in all female Wistar rats tested. Histological changes of the urothelium consisted of various degrees of hyperplasia and dysplasia. An infiltrating transitional cell carcinoma first appeared after 8 months. These results are compared with the findings of other authors, and divergencies of the tumour induction rates are discussed with respect to strain, sex and weight of experimental animals as well as concentration and amount of ingested carcinogen. Electron microscopy shows microvillous transformation of the luminal plasma membrane and appearance of a thick fluffy cell coat (glycocalyx). These changes are explained by an altered function of the Golgi complex occurring during malignancy and leading to a loss of the specific discoid vesicles of the urothelial cells.