Abstract

Mice were infected by feeding the embryonated eggs of Toxocara canis and Ascaris lumbricoides. Each mouse was killed daily for a week and then at several days interval after infection and the distribution of larvae in the various tissues of mice was investigated after the macerating the tissues and digesting with artificial gastric juice. It was confirmed that the migratory behaviour of larvae of T. canis and A. lumbricoides is referred to as the somatic and tracheal type of migration in the mice respectively. Toxocara larvae were found in the carcass on the third day after infection and in the brain after the sixth day of infection. From the thirty-fifth day to the seventy-sixth day after infection, Toxocara larvae were not found in the tissues of mice except in the carcass and brain and they did not develop further than the second-stage larvae. The size of Ascaris larvae, from the embryonated eggs was 0.228-0.271 mm length by 0.010-0.013 mm width and in the third day of infection the size of larvae was 0.271-0.343 mm length by 0.017-0.020 mm width. Between the fifth and tenth day after infection, lavrae molted twice in the lungs and grew to the fouth-stage larvae; 1.357-2.0 mm by 0.034-0.071 mm. These larvae migrated to the intestinal canal after the tenth day of infection and disappeared from the mouse after the twenty-fifth day of infection. No larvae were found in the carcass and brain. The inflammatory reactions in the tissues of infected mice were also observed.