Regeneration of Olfactory Mucosa in Mice after Inhalation Exposure to Perchloroethylene

An experimental group of 20 male pure-bred mice was exposed to perchloroethylene gas at 300 ppm for 6 h daily for 5 days. Histopathological study of the nasal mucosa, particularly the olfactory mucosa, was performed sequentially 2 weeks to 3 months after exposure, to clarify the process of regeneration. The tissue damage due to perchloroethylene gas was more persistent in the nasal mucosa of the olfactory region than in the respiratory region. Two weeks after exposure, ciliated epithelial cells, as well as normal pseudostratified nonciliated columnar epithelium, began to appear in the area previously covered by olfactory epithelium and remained for up to 3 months after exposure. A basement membrane was present under the ciliated epithelium, suggesting a possible persistence of basal cells. The olfactory epithelium may thus be replaced by ciliated epithelium. The lamina propria of the olfactory mucosa, however, lost its normal structure with atrophy of the olfactory nerves and Bowman's glands.