[ Histopathological changes in the thymus of the white mouse after infection with Toxoplasma gondii (author's...

Three days after infection of mice with a virulent strain of T. gondii first histopathological destructions of the thymus are visible. The number of lymphocytes decreases step by step till to the animals' day of death on the 7th day p.i. At this time the cortex has lost all its thymocytes. Electronmicroscopical pictures show destruction of most of the reticulum cells and lymphocytes. In those cells which are still alive multiplicaiton of Toxoplasma trophozoites is to be seen. A lot of parasites are lying extracellular in the detritus of the destroyed thymus-cells. After infection of mice with an avirulent strain of T. gondii there is a loss of lymphocytes in the cortex of the thymus too. Starting at day 5th to 7th p.i. it reaches its peak at the time of the 10th to 15th day after infection. After this period restitution of lymphocytes in the cortex is going on. At about the 30th day p.i. replacement of all the lymphocytes is finished. Sometimes the cortex seems to be enlarged, that means now there are more thymocytes in the cortex than in uninfected controls. Neither reticulum cells nor lymphocytes show destruction of their ultrastructure. Only a process of activation of the lymphocytes can be seen by electronmicroscopy. In the lymphocytes the mitochondria are enlarged and there are more than in the controls. At the same time Golgi-apparatus and endoplasmatic reticulum become prominent.