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.