SCANNING ELECTRON-MICROSCOPY OF DIMETHYLBENZANTHRACENE (DMBA)-TREATEDHAMSTER-CHEEK POUCH

The aim of the present study was to describe changes which could be re garded as a result of neoplastic rather than inflammatory processes. F ifty-five weeks after 6 weeks of DMBA application to the cheek pouches of 5 male hamsters there were 4 types of lesion: larger ulcerated ses sile; smaller non-ulcerated sessile; non-ulcerated pedunculated; conic al projections. These and the rest of the pouches were examined by sca nning electron and light microscopy. The interlesional mucosa, non-ulc erated sessile lesions and conical projections were covered by flat po lygonal cells with either a honeycomb surface pattern of interconnecti ng microridges, or microridges arranged into more parallel lines. Cell imprints and boundaries were formed by linear ridges, grooves or both . Pedunculated lesions had flat smooth-surfaced cells and cells with a honeycomb surface pattern. None of these lesions were carcinomas by l ight microscopy but the ulcerated sessile lesions were. The appearance of the cells on the ulcerated lesions varied: flat, with a variable n umber of short microvilli that were often knob-like, isolated short mi croridges, or both; plump, giving a cobblestone appearance with surfac es that were smooth, covered by microvilli, short microridges or both. Such appearances have been described as characteristic for dysplastic and malignant stratified squamous epithelium in a number of sites. Fu rther study of both experimental and naturally occurring mucosal disea se is needed to validate this.