Microwave-stimulated diffusion for fast processing of tissue: reduced dehydrating, clearing, and impregnating times.

In this paper we describe a method of preparing tissue blocks for paraffin sections within 30 min. The method is based on microwave-stimulated diffusion reducing the dehydrating, clearing, and impregnating times by a factor of 48. The developed technique was inspired by the experimentally observed sizable temperature-dependence of viscosity and other transport properties of liquids. It is clear that, by considering the theoretical aspects of diffusion and by analysis of the influence of the used chemicals in different tissue depths, histotechnical results can be optimized. The histotechnical microwave results are light-microscopically excellent and indistinguishable from those of the well-performed 'classical' method. The nuclear size of several cell types hardly differs in both methods. The new method is valuable in particular for individual cases in which a fast diagnosis is asked for, and in which a frozen-section diagnosis is thought to be too unreliable. In addition, this method can be used in small research laboratories processing small quantities of histological material. The only equipment needed to prepare tissue blocks of optimal quality is the microwave oven.