ABSTRACT
N-buty1-N-(4-hydroxybutyl)nitrosamine(BBN) is known to have a strong. specific carcinogenic action on the urinary bladder of rats. Rat bladder lesions induced by BBN are very similar to those of Pusan histopathologically. To investigate the surface change in the urinary bladder epithelium induced by 0.05% BBN scanning electron microscopic examination was done. Normal bladder epithelium was formed by relatively uniform sized. flat polygonal cells and clearly defined with intercellular ridges. in high magnification, the luminal surface of superficial cell consisted of hexagona1 areas and concave plaques between microridge giving a honeycomb appearance but no microvilli was visible. On BBN administration for 12 weeks, the superficial cells varied in size and shape and covered by numerous uniform round microvilli forming cobble stone appearance. On BBN administration for 12 weeks and water for 6 weeks, the superficial cells were covered with numerous microvilli completely. In some areas numerous pleomorphic microvilli were seen. Although pleomorphic microvilli are not a specific marker for neoplastic transformation, their presence is an indicator. of a markedly abnormal proliferative response.