Figure 9.

Model for the ability of bloodstream cells to differentiate based on their progression toward a differentiation-competent ST* state. For each cell type (pleomorphic, monomorphic, and differentiation-defective DiD-1; Did-1ΔGPI-PLC) the circle represents the cell cycle of the trypanosome, with the black box indicating the receptive window of the cell cycle at which parasites must accumulate to be able to differentiate. Cells must then progress toward an ST* state before transformation to procyclic cells either directly or via the morphologically stumpy form.