a histopathology study of caspian seal (pusa caspica) (phocidae, mammalia) liver infected with trematode, pseudamphistomum truncatum (rudolphi, 1819) (opisthorchidae, trematoda).

background: main objective of this study was to investigate the invasive activity of the liver fluke, pseudamphistomom truncatum against the caspian seal ( pusa caspica ) and was exemplified at the gross, light microscopy (lm) and electron microscopy (em) levels. methods: the study was done on a freshly dead caspian seal in the southern coast of caspian sea. the checked caspian seal probably being died of canine distemper virus and was found host to numerous parasites of four helminth species. results: p. truncatum caused edematous foci on the surface of the liver with prominent fluid accumulation. sections of the liver viewed with lm had mul-tiple necrotic areas with extensive hemorrhaging and disorganized hepatic lobules. granulocytes and invasion of connective tissue were prominent. whole worms were visible with invasive pathways through the host tissue. damage to both hepatic ducts and blood vessels were prominent. at the em level, organelles within the impacted hepatocytes were disorganized as exem-plified by the cristae of the mitochondria and the endoplasmic reticulum. par-asite eggs were scattered throughout the tissue. conclusion: it was shown that this trematode can be very pathogenic to caspian seal and as this only mammal of caspian sea is an endangered spe-cies; this needs more investigation toward control or possible treatment of this helminth.