Histopathological studies of acute, chronic and congenital infections of toxoplasmosis in mice.

The histopathological picture of Toxoplasma gondü RH strain (virulent) and Beverley strain (a virulent) was experimentally studied in mice. Nearly all the internal organs and tissues showed pathological changes ranging between the mild congestion to the severe degeneration. However, the changes were more serious in mice infected with RH strain than those infected with Beverley strain. The lungs showed massive consolidation and severe congestion. The heart showed hyaline degeneration of a cardiac muscle fibers. Focal areas of necrosis were seen in the liver, spleen and kidneys which were enlarged as well as in the cerebral cortex of the brain. The bone marrow and skeletal muscles were infiltrated by mononuclear inflammatory cells. The eyes showed mononuclear inflammatory cells in the retina consisted mainly of lymphocytes and the photo receptors were damaged. In congenital toxoplasmosis the brain showed perivascular mononuclear inflammatory infiltrate as well as multiple areas of necrosis. Microglial nodules were sometimes seen. The eyes showed no pathological lesion.