Photomicrographs of histological sections of mice inoculated with strains of Trypanosoma cruzi TcI (A, B, and C), TcII (D, E, and F), and TcIV (G, H, and I), in the early (A, D, and G) and late (B, E, and H) acute phases, and chronic phase (C, F, and I) of infection. Striated skeletal muscle showing tissue parasitism (strains AM44 - A, and AM45 - B), and intense focal inflammatory infiltrate (strain AM33 - C). Brain with nests of amastigotes (strain PR1219) (D). Cardiac muscle presenting tissue parasitism and mild diffuse inflammatory infiltrate (strain PR1219 - E), and tissue injury and moderate diffuse inflammatory infiltrate (strain BS48 - F). Liver displaying mild and focal inflammatory infiltrate (strain AM64 - G). Heart muscle with diffuse infiltrate mild (strain AM64 - H) and moderate (AM14 - I). The arrows point to the nests of amastigotes. All photos were taken at 400× magnification, hematoxylin-eosin.