An ultrastructural and morphometric study of bladder tumours (II).

Bladder tissues from 3 groups of patients were examined, using the light and electron microscopes (LM and TEM). One group of patients had a history of well-differentiated papillary transitional cell carcinomas and specimens were taken from cytoscopically normal areas. In a second group frank papillary carcinoma was biopsied. Finally, patients with no history of urothelial tumours and a normal cytoscopic appearance were biopsied during investigations for various benign conditions and these served as controls. In tissues from the first two groups certain differences were seen when these were compared to the controls and the frequency of these was significant. Light microscopic examination of 0.5 micros toluidine blue stained sections revealed an increased number of immature, small dark cells in the superficial layer of the epithelium (P less than 0.001). Electron microscopic examination showed that in place of the characteristic asymmetric unit membrane of mature superficial cells, the surface was frequently covered with microvilli and the junctional complexes were often atypical. There was an increased number of abnormalities in the basal lamina (P less than 0.001). These features were seen in the absence of cytoscopic and light microscopic changes in three out of eight patients with a history of tumours. It is, therefore, suggested that these are the earliest detectable morphological abnormalities in the pre-neoplastic urothelium.