Congenital toxoplasmic retinochoroiditis in the mouse--the use of the peroxidase anti-peroxidase method to demonstrate Toxoplasma antigen.

The peroxidase anti-peroxidase immunocytochemical staining method has been used to demonstrate Toxoplasma antigen within paraffin-embedded sections of the eyes of mice congenitally infected with Toxoplasma. Intact Toxoplasma tissue cysts were demonstrated within the retina but in no other ocular structure. No endozoites and no extra-cystic antigens were detected by this technique within any of the eyes examined. The possible implications of these findings in relation to the pathogenesis of toxoplasmic retinochoroiditis are discussed.