Fig. 2. Cellular morphology, percent cells undergoing apoptosis-like death and nuclear morphology of L. donovani promastigotes after exposure to 4 mM H₂O₂. (A) Morphology. (a) Promastigotes not exposed to H₂O₂. (b) Promastigotes exposed to 4 mM H₂O₂ for 6 hours. (c) Promastigotes exposed to 4 mM H₂O₂ for 12 hours. Bar, 10 µm. (B) Percentage of cells undergoing apoptosis-like death as counted by a combination of Hoechst dye and PI staining. Symbols: j, control; m, 1 mM H₂O₂; ., 4 mM H₂O₂; d, 4 mM H₂O₂ + catalase (100 IU ml^-1); r, 8 mM H₂O₂. (C) Changes in nuclei at different stages of cell death. Close ups of nuclei from a cell not exposed to H₂O₂ (a), a cell exposed to 4 mM H₂O₂ for 4 hours showing nuclear condensation (b) and a cell exposed to 4 mM H₂O₂ for 6 hours showing breakdown of nuclear material (c).