TEM images from longitudinal sections of root
tips of maize plants exposed for 0 (A and B) or 4 h (C–F) to
control (0 μm Al) (A–D) or 20 μm Al (E and
F) containing nutrient solution. A, C, and E, Glutaraldehyde-fixed
samples. B, D, and F, PA-stained samples. Note the abundance of
electron-translucent vacuoles with only some peripheric electron-dense
deposits (C and E, arrows) in conventionally fixed samples and the
abundance of electron-dense precipitates in the central part of
vacuoles from PA-stained samples (B, D, and F). All scale bars
represent 10 μm, except B, where bar is 1 μm.