Light and electron microscopic study of hamster cheek pouch treated with 9,10 dimethyl 1,2 benzanthracene and retinoic acid.

The present study reports light and electron microscopic observations of hamster cheek pouch epithelium exposed to 25 micrograms DMBA (DMBA = 9,10 Dimethyl, 1,2 Benz(a)-nthracene, RA = Retinoic Acid) and 25 micrograms DMBA along with 25 micrograms, 50 micrograms and 100 micrograms retinoic acid. Significant delay in tumour induction was observed in the animals treated with DMBA + retinoic acid. DMBA + retinoic acid treated cheek pouch developed papillary epidermoid carcinomas which were less invasive and less keratinized than only DMBA treated animals. At cellular level DMBA treated animals showed keratinized cells with thick bundles of tonofilaments, broken basement membrane, wide intercellular spaces and loss of desmosomal attachments, whereas animals treated with DMBA + retinoic acid showed decrease in the intercellular spaces, maintenance of basement membrane and intracellular organelles with suppression of keratinization, indicating the differentiating effect of retinoic acid on DMBA transformed cells of hamster cheek pouch.