[Splenic lesions in white mice due to Toxoplasma gondii endozoites in acute experimental infestation. A histological,...

The spleen of 73 white mice was studied (15 mice were studied by electron microscopy) from 24 to 120 hours after intraperitoneal infection. The successive stages of interaction of parasites with cells of mononuclear phagocytes system were observed. At the early stages of the infection the activation of these cells takes place. During the dissemination of endozoites over the host organism they penetrate the activated mononuclear phagocytes. Activation, however, is not effective enough since in these cells the parasites preserve the ability to hinder the fusion of lysosomes with phagosomes containing endozoites and at later stages of the infection of lyse the membrane of parasitophore vacuole. The ability to reproduce in activated mononuclear phagocytes and to lyse the membrane of parasitophore vacuole is regarded as a factor of the virulence of endozoites of RH strain toxoplasms.