Sebaceous metaplasia of rat oral epithelium during chemical carcinogenesis.

Application of the carcinogen 4-nitroquinoline N-oxide (4NQO) thrice weekly to rat oral mucosa led to development of free sebaceous glands in 91% of all carcinogen-treated animals. The palatal epithelium was the area of predilection. The entire process from the transformation of single basal cells to the formation of the multi-alveoli sebaceous glands could be followed in detail. Solvent-treated animals demonstrated only a few sebaceous glands in the gingiva of the maxillary first molars whereas control animals seemed devoid of these structures. It is suggested that de novo formation of free oral sebaceous glands is caused by a metaplastic process due to local irritants among which the carcinogen 4NQO seems particularly powerful. A correlation between sebaceous metaplasia and carcinogenesis could be demonstrated.