Measurement of BBN-induced alterations in rat urothelium by electron microscopic X-ray microanalysis.

The aim of this study was to analyse N-butyl-n-butanol-4-nitrosamine (BBN)-induced alterations of the urothelium in rats concerning its content of phosphorus, sulphur, chlorine, potassium and calcium using electron microscopic X-ray microanalysis (REM analysis). The following histopathological findings of the bladder mucosa were discovered after exposure to BBN: normal urothelium (n = 36); focal epithelial proliferations (n = 12) following 6-12 week's exposure; epithelial hyperplasia (n = 8) after urothelial carcinoma (n = 4) following 12 weeks' exposure. The observed phosphorus/sulphur and phosphorus/calcium ratios based on REM analysis did not show any statistical correlation with the morphological changes classified by light microscopy. Our data do not support the hypothesis raised by other investigators that an increase in phosphorus content or phosphorus/sulphur or phosphorus/calcium ratio could indicate early neoplastic transformations of urothelial cells as "tumor markers".