The effect of DMBA on hamster cheek pouch mucosa in vitro.

Neonatal hamster cheek pouch mucosa was treated with DMBA for three h either before being explanted or after 7 days in vitro. The epithelium of the treated cultures exhibited dysplasic changes, most marked at 21 to 28 days in vitro. These changes were not seen in the explants maintained for 35 to 49 days in vitro indicating a return to an apparently normal morphology. Examination of the ultrastructure of DMBA treated and untreated explants showed changes consistent with those described in similar tissues in vivo. The epithelium of the carcinogen treated tissue exhibited widened intercellular spaces, tortuous cell membranes, an irregular and discontinuous basal lamina and pseudopodia of the basal cells extending into the underlying mesenchyme. Similar changes have been described in inflamed epithelium, in some other experimental preparations, and in premalignant lesions in vitro, both in animals and man.