On the distribution and the growth of cyst of Toxoplasma gondii in the central nervous system and eyes of mice in the experimental infection.

Abstract

Mice which were infected with Beverley strain of Toxoplasma were examined for distribution and growth of the cysts in central nervous system as well as in eyes.1) The cysts were distributed throughout the central nervous system. Among four parts of central nervous system, the cysts were found most abundant-ly in telencephalon and cysts in medulla spinalis were the smallest in number. The largest number of cysts found in telencephalon was 134.52 per mg of the tissue.2) Number of cysts in central nervous system increased 1 to 2 weeks after the inoculation and it maintained the same level for several weeks. After 9th week of the infection the cysts began to decrease in number.3) Cysts in central nervous system continued to increase in diameter until 15th week of the infection. Cysts in cellebellum were the largest in size among those in 4 parts of the organ. The largest cyst in cellebellum was 107.9μ in diameter.4) Presence of the organism in eyes were examined in 34 mice. Cysts were detected directly from eyes in 25 cases and the organism was demonstrated from 5 cases only after subinoculation with the emulsified eyes into clean mice.5) The cysts in eyes were found only in the inner surface of retina. Cysts were also found in oculomotor muscles.6) Cysts in eyes were generally smaller in number as well as in size compared to those in central nervous system.7) No pathological findings were recognized in the tissue of eyes and central nervous system around the cysts.