Abstract
Experiments were performed to investigate the carcinogenic potential of Bracken fern (Pteris aquilina) using 211 rats, with pathomorphological assessment of vesical tumors. Groups of rats receiving bracken in feed developed neoplastic growths in the small intestines, subcutis, kidney and palate as well as in the urinary bladder, thus providing evidence for marked carcinogenicity of the plant. Histological observation revealed the development in the urinary bladder of papilloma (60 cases), transitional cell carcinoma (9 cases), squamous cell carcinoma (17 cases), adenocarcinoma (2 cases), fibroma (6 cases), leiomyosarcoma (2 cases) and hemangioma (1 case) showing benign to malignant properties. The tumors were more frequent and had greater degrees of malignancy in the groups receiving higher concentrations of bracken in feed. Of particular note in the development of epithelial tumors were hyperplasia of the epithelial layer and behavior of mast cells with associated edema of the mucosal epithelium and appearance of acidophilic spindle cells.
