ENCAPSULATED EGG DEPOSITION PATTERN OF SCHISTOSOMA-JAPONICUM IN THE PERITONEAL-CAVITY OF MICE

Thirty-four albino mice were each exposed to 20 cercariae of Schistoso ma japonicum by the intraperitoneal or percutaneous route and killed a fter 60-127 days. The peritoneal cavity of each mouse was flushed and worms in the portal vein system were perfused with citrated saline. Af ter sedimentation, washings were examined microscopically. Mature worm s were only found in the portal vein system. The worm recovery rate wa s much higher by percutaneous infection (61.2%) than by intraperitonea l (37.1%). The encapsulated egg granulomas were observed either in the peritoneal cavity or on the intestinal wall; the mean number of encap sulated egg granulomas was also higher in the former (1.6) than in the latter (0.6). The average number of eggs per granuloma was very simil ar by both routes (10.7 and 11.4). The mean size of encapsulated egg g ranulomas (529 mum) was increased correspondingly with the number of e ggs (range 181-985 mum). The percentage of viable eggs within the gran ulomas in the peritoneal cavity (77%) was much higher than those on th e intestinal wall (18%). Encapsulated egg granulomas were usually ovoi d although some had an irregular shape.