Ultrastructure of N-dibutylnitrosamine-induced tumors of the urinary bladder in European hamsters.

European hamsters were treated sc with 0.025 the median lethan dose of N-dibutylnitrosamine. The induced neoplasms of the urinary bladder (transitional cell carcinomas and squamous cell carcinomas) were examined electron microscopically. Their ultrastructure indicated these tumors to be different developmental stages of the same type of tumor rather than two fundamentally different types of neoplasm.