Rapid cold fixation of tissue samples by microwave irradiation for use in electron microscopy.

A cold microwave irradiation procedure was developed to fix rapidly and stain various tissues and monolayers for electron microscopy. Because microwave stimulation always produces some heat, melting ice was used to maintain the temperature of the tissue samples, the fixative, and the staining solution at 0 to 4 degrees C. The low temperature also reduced vapour formation, thus minimizing the risk of explosion. The microwave method shortened the total time of fixation and dehydration from the usual 3 h required by the conventional method to 65 min. After microwave fixation, the ultrastructural details of membranes and subcellular structures were excellent.