High-magnification CLSM detection of superoxide anion (O
.-) with DHE at different developmental stages of the olive flower, A: projection of section stacks of the stigma surface at stage 3. The fluorescence localizes in association with the stigmatic papillae. B: stacks projection of the surface of the distal area of the stigma at stage 4. C: stacks projection of the surface of the central area of the stigma at stage 4. Note the differences in both the texture of the exudate, and the intensity of the labelling. D: optical section of several pollen grains on the stigmatic surface at stage 4. Several clusters of pollen organelles are intensely labelled (red arrows). E: optical section of several pollen grains germinating on the stigmatic surface at stage 4. The cytoplasm of the pollen tube appears weakly labelled. However the fluorescence becomes more intense in the contact areas between the pollen tube and the papillae (yellow arrows). E: projection of section stacks of the anther at stage 4. Fluorescence localizes in the stomium. The pollen grains show red autofluorescence. Ex: exudate; p: papillae; Pg: pollen grain; Pt: pollen tube.