Effect of SEM processing on dimensions of A. thaliana , cotton and barley leaf tissue. Loss or gain in tissue area after processing through to critical point drying is expressed as percentage of original (fresh) tissue area. Treatments: FAA = FAA fixation; Glut = 3% glutaraldehyde; 70 eth = 70% ethanol fixation; Meth = Methanol fixation and dehydration followed by critical point drying in methanol; Meth-eth = methanol fixation followed by ethanol dehydration; 100 eth = absolute ethanol fixation; Acet = acetone fixation followed by ethanol dehydration (details in text). Bars are standard errors, 10 replicate tissue pieces were processed for glutaraldehyde, FAA, 70% ethanol and the 2 methanol treatments, and 16-20 replicates were processed for the absolute ethanol and acetone treatments. Only acetone treatment of A. thaliana leaf pieces resulted in overall tissue swelling (i.e., an average positive value), indicated by a dark grey-filled bar. Arrows indicate treatments in which some replicates swelled and others shrank, giving large standard errors.