Abstract
This chemically induced carcinogenesis experiment was performed for purposes of preliminary experimenting for further oral carcinoma studies. Painting 0.5% DMBA in liquid paraffin into six-week-old Golden Syrian Hamster's buccal pouches, threetimes a week for 14 weeks, the following results were elucidated.
Within the first 4 weeks, inflammatory reactions of the mucosa, i. e., redness, formation of plaques, and bleeding were found. Thereafter, they naturaly disappeared from around the 5th to the 6 th experimental weeks. On the 8 th week, papillomatous tumors suddenly appeared which were growing gradually in size, number, and even in atypism. The surrounding epithelia showed changes comparable to epithelial dysplasia or carcinoma in situ. It was from the 12-week-painted group that well-differentiated squamous cell carcinomas were-first recognized.
These tumors were rather exophytic growths and showed a minimal invasive trend. However, invasive tumors were formed as well in the 14-week-painted group. Therefore, two possible ways for carcinoma formation might be suggested. One is from papilloma through increased atypism, such as verrucous carcinoma, and the other from epithelial dysplasia or carcinoma in situ with downward growth of the rete-processes to the carcinoma.
