Four leaf preparation techniques (air drying, tetramethylsilane
air drying, critical point drying, and freeze substitution)
used in scanning electron microscopy (SEM) were evaluated with
respect to the degree of cellular distortion they produce in
stomatal guard cells of leaves of Dactylis glomerata
and Elymus canadensis. Surface morphological distortion
and cuticle disruption in the air-dried and tetramethylsilane
air-dried leaves, and cuticle disruption within the critical
point-dried tissue made it difficult to obtain measurements.The
freeze-substituted tissue experienced little cuticle disturbance,
and the cellular morphology appeared normal. The length of the
guard cells did not significantly differ between the air-dried,
tetramethylsilane air-dried, critical point-dried, or
freeze-substituted samples. Widths did significantly vary, with
the freeze-substituted tissue having lower values than tissues
treated with the other treatments. Freeze substitution methodology
produced SEM images that appear to be less distorted and allow
easy and precise measurement.