Dm500b compound microscope

To visualize cellulose, resin-embedded thick-sections (1 μm) were placed on glass slides and incubated for 3-5 min in a drop of Calcofluor White (Sigma-Aldrich) and a drop of 10% KOH buffer in the dark. Calcofluor White is a fluorescent dye specific for fibrillar β(1→4) glucans of plant cell walls such as cellulose (Maeda and Ishida 1967). In order to localize callose, 1-1.5 μm sections were collected on slides, covered by 1% aniline blue in 0.067 M Na₂HPO₄ (pH 8.5), placed in the dark at 4 °C for 3-5 days, and rinsed in buffer. Controls were made using the respective buffers without aniline blue or Calcofluor White. Three replicates were made for each treatment and controls. All stained material was viewed with a Leica DM500B compound microscope (excitation filter equipped with ultraviolet fluorescence between 360-400nm). Images were collected digitally using a Q-Imaging Retiga 2000R digital camera.