Dimensional stability in tissues dehydrated with 2,2‐dimethoxypropane for electron microscopy

SUMMARY Dimensions of tissues fixed in glutaraldehyde‐osmium tetroxide mixture, osmium tetroxide and uranyl acetate and then dehydrated in 2,2‐dimethoxypropane (DMP) were measured using transmission and scanning electron microscopy. Rat cardiac muscle, kidney and other tissues were examined in this study. The mean dimensions of characteristic ultrastructural features of material prepared by this method are similar or larger than those reported in the literature for conventionally processed samples. Critical point drying of specimens dehydrated with DMP does not produce abnormal shrinkage. Simultaneous primary fixation of lipids and proteins in a glutaraldehyde osmium tetroxide mixture and omission of the water wash after uranyl acetate appear to be important in stabilizing the tissue for rapid dehydration. The rapid reaction of DMP and water yielding the products acetone and methanol does not appear to denature tissue components to a greater extent than conventional solvent exchange dehydration.