Histological lesions observed in Toxoplasma gondii infected mice. A Brain. Mouse infected with the TgShSp16 strain. Note, the tissue cyst-like structure (arrow) and non-purulent vasculitis (arrowhead). B Lung. Mouse infected with the TgShSp24 strain. Note, the perivascular infiltration of non-purulent inflammatory cells (arrow) and focal thickening of the alveolar wall (arrowhead).