An inhibitory effect of vitamin A on the induction of tumors of forestomach and cervix in the Syrian hamster by carcinogenic polycyclic hydrocarbons.

histology of certain types of epithelium is well-known (1, 5, 6). A deficiency of this Vitamin induces metaplasia which is especially noticeable in the bronchial epithelium and the uterine cervix (9). Marked keratinization is a common feature of this metaplasia (7). Adequate dietary vitamin A, on the other hand, reportedly inhibits keratini zation and prevents deficiency-metaplasia (3). The pur pose of the present study was to see what effect the ad ministration of large doses of vitamin A would have on the response of epithelium to carcinogenic polycyclic hydro carbons in Syrian hamsters.