Three-dimensional images of T. gondii cysts containing CD8+ T cells that had fully invaded into the cysts detected in the brains of infected nude mice that received a transfer of CD8+ immune T cells. Sections (4 um thick) of their brains were applied for immunohistochemical staining for T. gondii (brown) and CD3, the T cell marker, (red), and Z-stack images were obtained using light microscopy. Upper panels show the images taken at the top and bottom of the histological section. The presence of the T cells (arrows) can be seen in both images at the top and bottom of the section. The lower panel shows a 3-dimensional image generated from the Z-stack images of the cyst at the cut-line indicated by a green arrow and line. These Z-stack images demonstrate the presence of the T cells (arrows) all the way through the sections. Scale = 10 um.