THE 2-STEP VACUUM-MICROWAVE METHOD FOR HISTOPROCESSING

When microwaving and vacuum is combined, decrease of boiling temperatu re can be exploited in the histoprocessing procedures allowing a compl etely novel approach for impregnating tissue with paraffin. We found t hat, if the pressure is sufficiently low in the paraffin step, no ethy l-alcohol step is necessary for the dehydration. In that case, the fix ed tissue blocks can be directly placed into the isopropanol and, afte r that, in the hot paraffin, in which the final dehydration of the tis sue takes place. The full histoprocessing procedure can thus be shorte ned into two steps only, with a processing time (for 72 biopsies) of a mere 40 min. Working completely without ethyl alcohol might be of int erest for countries in which ethyl alcohol is difficult or expensive t o obtain. We conclude that vacuum-microwave histoprocessing allows us to omit ethyl-alcohol dehydration and to replace xylene, resulting in a two-step 'green' (ecological) method.