EFFECT OF ADDITION OF DRIED HEALTHY OR DISEASED PARSNIP ROOT-TISSUE TO A MODIFIED AIN-76A DIET ON CELL-PROLIFERATION AND HISTOPATHOLOGY IN THE LIVER, ESOPHAGUS AND FORESTOMACH OF MALE SWISS-WEBSTER MICE

Umbelliferous crop plants, including the parsnip (Pastinaca sativa L.) , elaborate enhanced levels of furocoumarins, including psoralens, whe n subjected to biotic or abiotic stress. These furocoumarins are recog nized to lead to phototoxicity. In this study, the effect of these age nts, which are present in diseased parsnip root tissue, on the liver a nd two tissues on the route of entry to the body (the oesophagus and f orestomach) were investigated. Young male Swiss Webster mice were fed for approximately 30 days with modified AIN-76A diets containing 32.5% dried healthy, 32.5% apparently healthy or 32.5% fungicide-treated pa rsnip root tissue, and 8, 16 or 32.5% dried diseased (Phoma complanata -infected) parsnip root tissue. As controls, three modified AIN-76A di ets differing in their edible starch-to-sucrose ratios (C1-C3) were ad ministered for an equal time. Dried healthy parsnip root tissue, compa red with controls, did not significantly affect any of the indices of cellular proliferation or histopathological parameters that were asses sed. Histopathological examination of the oesophagus and forestomach d emonstrated no significant changes as a result of feeding any of the d iets containing parsnip tissue. In the liver, the highest level (but n either of the two lower levels) of dried diseased parsnip root tissue led to swelling of the cytoplasm in cells surrounding the central vein of hepatic lobules, with consequent compression of the peripheral cel ls. Using H-3thymidine radioautography, a dose-related increase in c ell labelling with the level of diseased parsnip root tissue was demon strated in the liver. Compared with control diet C2 only, the extent o f H-3thymidine labelling in the liver was increased in mice receivin g apparently healthy parsnip tissue; a slight, not statistically signi ficant, increase was also noted with fungicide-treated parsnip tissue. Increased H-3thymidine labelling with the feeding of diseased parsn ip tissue was also found in the greater curvature of the forestomach a nd the region of the oesophageal-forestomach junction, but not at the glandular junction of the forestomach nor in the mid-oesophagus.