Optimum fixation conditions may allow air drying of soft biological specimens with minimum cell shrinkage and maximum preservation of surface features.

This paper focuses on the concept that traditional SEM artifacts, encountered in soft biological specimens, may be overcome by improving the physico-chemical properties of these samples rather than by applying sophisticated drying procedures. Emphasis is placed upon fixation strategies minimizing these artifacts and allowing the air drying of various specimens, even those showing very delicate surface microprojections. This attitude is illustrated by a variety of cells and tissues prepared for SEM by both conservative (i.e., critical point drying of samples treated with glutaraldehyde and/or osmium tetroxide) and reformative procedures, i.e., air drying of samples treated with glutaraldehyde, tannic acid, guanidine-HCl, and osmium tetroxide (GTGO-AD). The results clearly indicate that samples which were prepared by the GTGO procedure displayed very well preserved surface features with minimum shrinkage, even after being air dried.