a single dose ( 0.25 mg ) of the carcinogen n-methyl-n-nitrosourea ( mnu ) when instilled directly into heterotopically transplanted urinary bladder ( htb ) induced a 9 % ( 2 of 22 ) incidence of urinary bladder tumors by 30 weeks in the urine free htb environment , whereas repeated instillation of urine into the htb after mnu treatment resulted in a 61 % ( 14 of 23 ) incidence of these tumors .
C0005695
of urinary bladder tumors
C0005682
htb