Sequential morphogenesis of urinary bladder tumors in BALB/c mice given 2-acetylaminofluorene

The sequential morphogenesis of bladder tumors induced in mice with 2-acetylaminofluorene were studied in order to understand better the morphogenesis of bladder tumors in humans. The study indicated 2 distinct patterns in the sequential morphogenesis. The first was a focal neovascularizaton of the transitional epithelium resulting initially in exophytic nodules which appeared more likely to develop into papilloma. The second was a nodular downgrowth of the transitional epithelium resulting initially in endophytic tumors which progressed to endophytic and exophytic carcinomas. Further work is needed to explain the significance of the 2 separate pathways which sometimes led to the same end result.