Figure 4. Subpodocyte space pseudocysts form during treatment with MTZ.

2-PM of 0.5 mg/ml Hoechst 33342 and 25 mg/ml TRITC-dextran injected Chet larvae at 5 dpf revealed pseudocysts (a, arrowhead, scale bar represents 10 μm) within the cell bodies and nuclei that were pushed aside (a). The parachute-like pseudocysts have a basal opening to the GBM and are encapsulated by podocyte cell bodies (a, arrow). The striped Hoechst signal in capillaries is due to blood flow of nucleated erythrocytes in living larvae (representative images of n = 4 individual experiments, scale bar represents 5 μm). The appearance of pseudocysts was consistent with findings in confocal laser scanning microscopy of cross sections after 3 hours 5 mM MTZ treatment of 4 dpf Chet larvae as seen in picture (b), while control treated larvae did not show any pseudocysts (Supplementary Figure 6b,c, representative images of n = 3 individual experiments). Transmission electron microscopy further revealed the ultrastructural composition of these pseudocysts as exemplarily shown in picture c. Injured podocytes showed a basal opening to the GBM (yellow) and large pseudocysts (blue) which were encapsulated by the podocyte cell bodies (scale bar represents 1 μm, representative image from n = 3 experiments).