The tracheal mucous membrane of normal, viral bronchotracheitis of human was observed by using scanning electron microscope. In addition experiments by using poisonous gas (Mustard) inhaled into mice was done. Normal tracheal mucous membrane was covered with beautiful ciliated cells, non ciliated cells and goblet cells. Near the top of the cilia microfilament-like structure was seen. The tracheal mucous membrane of tracheitis by viral infection taken at the autopsy was severely deteriorated. The ciliated cells and goblet cells had disappeared from the tracheal mucous membrane and only the basal cells remained on the basal membrane. Many basal cells had also disappeared from the basal membrane. On the tracheal mucous membrane of bronchotracheitis patients, the cilia had decreased and the enlarged tracheal ducts and increased mucous balls were observed. In the Mustard inhaled mice, the tracheal mucous membrane was severely damaged. The cilia of tracheal epithelium were almost gone, the surface of non ciliated cell was also deteriorated. The regeneration of cilia sprouted about 2 weeks later.
