Abstract
Morphological changes on the epithelium of the tracheal mucosa of DS-mice which had been exposed continuously in SO2 of low concentration as well as in NO2 were observed by mean of SEM, in comparison with the results by TEM and ultra-thin-section technique in LM. In exposed group, each cilia became undistinguishable, short, adherent and rough, and lost the directionality of the metachronal weve. While, non-ciliated cells were generally in accelerating stage of mucous secretion which we classified into four phases; preparing, beginning, increasing and terminal phase respectively.
