Quantitative Stereology: Toxicologic Pathology Applications

1 NTRODUCTION Quantitative stereology concerns a specialized area of microscopic image analysis in which measurements of objects can be accurately obtained by means of rationalized steps of sampling combined with mathematical reconstruction. However, the quantification of microscopic tissue changes has not received widespread, general use among microscopists although the application of these techniques represents tangible benefits. This paper is aimed at presenting a brief survey of current concepts and discussing some practical applications, in order to stimulate our colleagues in Toxicologic Pathology. The mathematical reconstruction of two-dimensional tissue sections is a valuable technique which can be used in toxicologic pathology research to characterize equivocal changes in the structure of tissues as well as identifying dynamic changes in subcellular organelles. Quantitative stereological analyses of solid bodies are based upon statistical derivations of geometric probabilities. The development of morphometric models for the analysis of tissue changes requires basic, but justifiable assumptions, allowing characterization of structures with complex shapes. An example of such a stereological assumption is represented by hepatic mitochondria (Figure 1) that approximate right circular cylinders in shape (12), although their profiles appear ellipsoid. Hence, reasonable and justifiable geometric models and associated mathematical formula provide a means of inference as to structure of cellular aggregates in the tissue and associated organelles within the cytoplasm or in isolated subcellular fractions (1).