Histopathologic responses of the jird, Meriones unguiculatus, to the bile duct and pancreatic trematode, Brachylaime microti.

Biliary tract histopathologic responses of the Mongolian jird, Meriones unguiculatus, were monitored during infection with Brachylaime microti. At 15 days postinoculation (PI), an inflammatory cell (polymorphonuclear and band neutrophil) response occurred in periductal tissue of the common bile duct at the site of oral sucker attachment; basophils and eosinophils were not observed. Capillary prominence and fibroblasts also were noted in this region. Histologic evidence suggested an immunologic response had begun by 15 days PI; massive periductal lymphocytic infiltration occurred and enlarged mesenteric lymph nodes adjacent to the pancreas contained proliferating lymphocytes. Hepatocyte vacuolation was noted at this time. By 30 days PI, the bile duct epithelium had invaginated and lymph nodes were enlarged further. At 65 days PI, worms were encapsulated in small intrahepatic ducts by fibrous tissue of host origin. Gastric peritoneal mesothelial cysts containing ova were seen in one host. Pancreatitis was not observed in response to infection with B. microti.