The development of squamous cell metaplasia in human bronchial epithelium by light microscopic morphometry.

Bronchial biopsies from ten subjects, including five smokers, have been examined using light microscopic morphometry. The biopsies were free from identifiable disease. Using manual point counting and a Quantimet 720 image analysing computer, a number of parameters were measured. Computer-based cluster analysis of seven of these parameters associated the subjects into three groups: visual inspection of the sections achieved the same separation. Four subjects (non-smokers) had normal epithelia: four subjects (one non-smoker, three smokers) showed mucous cell hyperplasia: two subjects (smokers) had squamous cell metaplasia. Three parameters in conjunction contained sufficient information to characterize accurately the histological appearance of the epithelia: the epithelial thickness, the volume density of intracellular mucus and the number of nuclear profiles per unit area of sectioned epithelium. Reduction of these three parameters to a linear plot closely approximated a similar reduction of the original seven parameters. These three parameters can be measured rapidly, either manually or by the Quantimet. The linear representation of these parameters provides a reproducible and objective basis for comparing specimens of bronchial epithelium.