ABSTRACT
Morphometry is an indispensible tool for the proper evaluation of peroxisome proliferation (Moody and Reddy, 1976; Staubli et al., 1977). In the classical morphometric analysis of cell organelles, however, a large number of electron micrographs is needed and these must be analysed by means of the manual pointcounting technique (Weibel, 1979). We have shown the feasibility of using light microscopic DAB-stained sections in conjunction with computer-assisted televisionbased image analysis for the morphometric estimation of peroxisome proliferation (Fahimi et al., 1982; Beier and Fahimi, 1987). The method is simple and provides reliable results, but the absolute values for peroxisomal volume density are, without a correction for section thickness, substantially higher than those obtained by electron microscopic morphometry. Moreover, the light microscopic approach underestimates the proliferation of peroxisomes because of the lower resolution and because of the greater overlap of particles in 1 µm sections (Beier and Fahimi, 1987). This could account for the rather moderate increase in the peroxisomal volume density in rat liver (3.5-fold) found in the present study. Nevertheless, in comparison with any other study (Moody and Reddy, 1976; Stäubli et al., 1977) the differences in potency and the dosage of the drugs tested must be taken into consideration.
