Morphometric evaluation of bronchial glands of beagle dogs

Using lung tissues of beagle dogs, we developed a method for objective estimation of bronchial glands. Defined generations (5th, 10th, 15th and 20th) of bronchi were collected according to the microdissection method by Plopper et al. (1983) [1]. Transverse sections were prepared for both light microscopic and electron microscopic studies. The point counting using prints made by a video copy processor was performed for estimation of the volume density of bronchial glands. Bronchial glands were observed throughout the canine bronchial tree. Moreover, a distinct difference was found in the volume density of bronchial glands depending on the lobe examined and the generation number. Recently, we performed a long-term inhalation study using beagle dogs in order to elucidate toxic effects of sulfur(IV) and acidic sulfate aerosols (Heyder et al., 1994) [2]. In addition to the quantitative analysis of surface epithelia, the volume density of submucosal glands in the bronchial wall was measured according to the method described above. As preliminary result, there was a tendency to an increased volume density of glands in the exposure group. Detailed quantitative evaluation of bronchial glands may enable detection of finite changes induced by low level concentrations of air pollutants.