Effects of Topically Applied 5-Fluorouracil in the Syrian Hamster

A microscopic and histologic comparative analysis of the effects of topically applied 5-FU on the skin and buccal pouch of the Syrian hamster revealed a marked difference in response. Anesthetized Syrian hamsters were treated daily with 0.5 mg of 5-FU for 14 consecutive days. Gross and microscopic examinations reveled that the skin was unaffected by this therapy. Macroscopic changes of the buccal pouches were noted 24 hr after therapy was initiated and microscopic evidence of erythema was noted at the end of a days. Mitotic figures and an inflammatory cell infiltrate noted after 3 days were completely absent in later specimens. An epithelial connective tissue defect with ulceration and necrosis was evident by the end of 7 days. Nine-day and 14 days specimens showed severe epithelial connective tissue separation and condensation of the underlying connective tissue. Animals allowed to recover after 14 days of therapy showed complete reepithelization by the end of 34 days