ELECTRON MICROSCOPIC STUDY ON THE CHRONOLOGICAL CHANGES OF THE EXPERIMENTAL BLADDER CARCINOGENESIS

Abstract

We have reported bladder cancers of BALB/c mice after oral administration of N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). The present study describes chronological changes observed by electron microscope in the process of bladder carcinogenesis of mice after BBN treatment.
The following findings became evident with the development of neoplasia: increase of nucleocytoplasmic ratio, enlargement of nucleoli, increase in number of free ribosomes, polysomes and fasciculated tonofilaments, mitochondria showing enlargement or vacuolation and appearance of mitochondria with inclusions.
The distinct asymmetric unit membrane (AUM) of the vesicles and luminal surface of the mucosal cells of normal untreated mice was decreased in hyperplastic mucosal cells and was not recognized in overt cancer cells. Angularity of the surface membranes of normal cells became less apparent in hyperplastic mucosal cells and microvilli-like structures appeared in the neoplastic cells.