EXPERIMENTAL STUDIES ON THE PATHWAY FOR MIGRATION AND THE DEVELOPMENTOF TAIWAN TAENIA IN DOMESTIC PIGS

The pig is the most favorable experimental intermediate host of Taiwan Taenia. Cysticerci in infected pigs are located in the liver except f or a few extrahepatic ones. The present study was designed to investig ate the pathway of migration-of the oncospheres of Taiwan Taenia in th e pig. In the first group, each of 5 Small-Ear-Miniature (SEM) and one Landrace-Small-Ear-Miniature (L-SEM) pigs were injected with 5000 hat ched oncospheres into the ear vein. Three SEM and one L-SEM pigs were found to harbor 88 degenerated or calcified cysticerci only in the liv er 51-81 days after injection. In the second group, each of 3 L-SEM pi gs were injected with 5000 hatched oncospheres into the jugular vein. One of the 3 pigs was found to have 5 cysticerci (2 mature and 3 degen erated or calcified) only in the liver at 89 days post-injection. In t he third group, each of 4 SEM, three L-SEM, and 3 L-SEM pigs were inje cted with 10,000, 10,000, and 5000 hatched oncospheres, respectively, directly into the portal vein after surgical opening of the abdominal cavity. All 10 pigs were found to be infected with a total of 1088 cys ticerci (44 mature and 1044 degenerated or calcified) only in the live r 23-62 days after injection. Although the sites of injection in these three groups were different, the liver was the only final location of the cysticerci. These findings give strong evidence that the oncosphe res migrate to the liver through the venous circulation and develop in this organ.