Structure of the tissue cyst and bradyzoite

The structure of the mature tissue cyst observed from 3 to 24 months following infection (approximately the lifespan of the mouse) remained relatively unchanged (Figure 2.23D). The first important observation is that throughout this period the tissue cysts are retained within a viable host cell (Figures 2.23D, 2.23E). It had originally been thought that the mature cysts are extracellular; however, on ultrastructural examination a thin rim of host-cell cytoplasm could be observed enclosing the tissue cysts (Ferguson and Hutchison, 1987b). This may explain the lack of an immune response to the tissue cysts; they are masked by the host cell. With the limited host-cytoplasm available, it is difficult to identify the cell type; however, in the majority of cases the host

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