Nonchemical dehydration of fixed tissue combining microwaves and vacuum.

A novel histoprocessing method for paraffin and plastic sections is presented in which dehydration of fixed tissue blocks is achieved within 5 minutes by microwaving under vacuum. Exploiting the decrease in boiling temperature under vacuum, we succeed in evaporating liquid molecules in the tissues at physiological temperatures. In this microwave-vacuum dehydration method, the fixed tissue does not come in contact with ethyl alcohol. For the paraffin method, the nonchemically dehydrated tissue is directly placed in the intermedium isopropanol prior to embedding. For the resin method, it is directly placed in the monomer solution. With this method, microscopical imaging can be brought closer to the in-vivo situation as is illustrated in liver and kidney sections. In principle, this microwave-vacuum dehydration method can also be used for ultrastructural studies.