Effect of accelerating voltage on BSE imaging of cell wall outlines in critical point dried A. thaliana rosette leaf. The same area of a leaf was imaged at accelerating voltages 10 (A), 15 (B), 20 (C) or 30 kV (D). Arrowheads indicate cell wall boundaries, arrows indicate chloroplasts in mesophyll cells. Chamber pressure 10 Pa. Scale bar = 60 μm (A–D, bar shown in D).