Pathological evaluation of Polystichum squarrosum (D. Don) fern in laboratory rats.

: Polystichum squarrosum fern fed (30% w/w) rats showed moderate mortality, decrease in body weight, less body fat and splenomegaly. On post-mortem examination, significant gross lesions were not seen in sacrificed animals. Histopathologically, Polystichum fed rats showed dilated Virchow Robin's space in brain, mild to moderate vascular changes likeoedema, engorgement of blood vessels and haemorrhages in most of the visceral organs, interstitial pneumonia in lungs, focal necrosis and generalised vacuolative degenerative changes in liver, more haemosiderin deposition and presence of higher number of megakaryocytes in spleen, shrunken glomeruli, more peri-glomerular space and more number of glomeruli per microscopic field in kidneys, focal hyperplasia of urinary bladder and moderate to marked depletion of germinal epithelium and spermatids in seminiferous tubules of testes. Pathologically, progressive changes were observed only in liver, urinary bladder and testes on 180 days post feeding (DPF). One fern fed rat sacrificed on 135 DPF showed hepatic tumour which was diagnosed as hepatocellular carcinoma. The results showed that P. squarrosum produced almost comparable pathological changes/preneoplastic lesions as reported in bracken fern fed animals. Long term exposure studies (i.e. 2 yrs) are desired.