Skeletal muscle capillary ultrastructure in Toxoplasma gondii parasitized mice

A light and transmission electron microscopic study was performed in skeletal muscles from mice experimentally infected with Toxoplasma gondii. Parasite cysts were not observed. Capillary endothelial cytoplasm abnormalities included proliferation of organelles, decrease of pynocytic vesicles, degenerative changes and necrosis. In some capillaries the lumen was reduced or absent. Pericytes also were altered. In all animals (n = 13), the basement membrane was normal. The cellular infiltrate consisted of macrophages, lymphocytes, mastocytes and eosinophils. The alterations observed in muscle microvasculature in absence of Toxoplasma gondii cysts, could be due to a host-immune response to the parasite.