Immunohistochemical diagnosis of toxoplasmosis in fetuses and fetal membranes of sheep.

A peroxidase antiperoxidase technique was developed for visualizing intact Toxoplasma gondii and its antigenic residues in sections of formalin-fixed, paraffin-embedded tissues from fetal membranes recovered from ewes with induced toxoplasmosis. The peroxidase antiperoxidase method was specific and sensitive, allowing the detection of T gondii antigen even in severely decomposed tissues. Toxoplasma gondii infection was most commonly demonstrated in the cotyledons, heart, lungs, brain, and skeletal muscles of the fetus.