DETECTION OF SILICA PARTICLES IN LUNG-TISSUE BY POLARIZING LIGHT-MICROSCOPY

The detectability of silica particles in ordinary histologic sections by means of polarizing light microscopy has been controversial. Throug h the application of both correlative light microscopy and scanning el ectron microscopy to different lung sections, we showed that particles demonstrating peaks for silicon only by energy-dispersive x-ray micro analysis were in fact visible by polarizing light microscopy. These pa rticles included some silica particles less than 1 mu m in diameter. W e found no correlation between the intensity level of the light source used for polarization and the differential ease of visualizing silica versus silicates; examples of both could be detected at both relative ly low and high light intensities. This suggests that geometric parame ters may be as important as composition in the ease of detection of si lica versus silicates with polarized light.