STEREOLOGICAL METHODS - A NEW APPROACH IN THE ASSESSMENT OF PULMONARY-EMPHYSEMA

In order to develop a reliable and sensitive method for studying the d evelopment and progression of pulmonary emphysema, we compared stereol ogical indices with the usual index for grade of emphysema, i.e., the mean linear intercept (Lm), in elastase-induced emphysema in mice. The Lm and stereological indices, including volumes of total lung tissue (Va((It))), airspaces (V-(air), and surface area of alveolar walls (S- (alv)), were determined in 5-mu m, H&E-stained, paraffin-embedded lung sections from elastase- (n = 7) or saline-treated (n = 8) mice. The i ndices were measured by point counting, using Cavalieri's principle (V -(It)) and V-(air)) or by counting intersections of alveolar walls wit h test lines of a known length (S-(alv) and Lm). Elastase treatment re sulted in a significant increase of Lm and of V-(air) both indicating airspace enlargement, and in a significant decrease of V-(It) and S-(a lv), indicating destruction of alveolar walls. Between each of the ste reological indices and the Lm, significant correlations were found whe n all lungs were included, but not when the emphysematous lungs were c onsidered separately. We conclude that stereological methods can be po werful morphometric tools for studying pulmonary emphysema development and progression, since they give information not only about the grade of airspace enlargement but also about the grade of destruction of al veolar walls. Based on this unique property, stereological methods als o allow a distinction between pulmonary emphysema and unrelated condit ions with dilatation of airspaces only. (C) 1996 Wiley-Liss, Inc.