The effects of vitamin A-deficient diets containing lactose in producing bladder calculi and tumors in rats.

This report describes studies in which diets have been developed which when fed to rats commonly result in the formation of primary urinary bladder calculi. The bladder walls of most of these rats but not those without urinary stones were grossly hypertrophied. Microscopic examinations in one of the studies indicated that about a quarter of the bladders containing stones showed histological changes consistent with those characterized as grade I to II transitional cell carcinomas. In all cases animals showing these histological abnormalities consumed vitamin A-deficient diets in which the carbohydrate was supplied mostly by lactose.