Paraffin Compression Due to the Rotary Microtome

Abstract

The extent of compression of microtome sections has been studied for blocks with tiss. and also blocks of clear paraffin. Thick sections are commonly compressed 15% or more; in sections below 5 or 10 /[mu] compression may exceed 50%. Compensatory thickening of sections occurs. The degree of compression for various paraffin samples and for various conditions of knife edge, temp., etc., is compared. Microscopical work, particularly where quantitative data or reconstructions are involved, is often seriously impaired by unrecognized artifacts of sectioning. The present work indicates the magnitude of such artifacts. Compensation for distortions of sections is not easy because tiss., particularly dense tissues, may compress less than the paraffin matrix. Section corrugation is due to this inequality in compression. Absorption of water in section flattening causes some tiss. readjustment, but this varies with different tissues and different fixations.