Mucous cell metaplasia in rat nasal epithelium after a 20-month exposure to ozone: A morphometric study of epithelial differentiation
- Michigan State Univ., East Lansing, MI (United States)
The present study was designed to examine the effects of long-term ozone exposure on nasal epithelia and intraepithelial mucosubstances (IM) throughout the nasal airways of F344/N rats. Animals were exposed to 0 (controls). 0. 12. 0.5, or 1.0 ppm ozone. 6 h/day, 5 days/wk. for 20 mo. Rats were killed 1 wk after the end of the exposure. and nasal tissues were processed for light and electron microscopy. Standard morphometric techniques were used to determine epithelial cell densities and the amounts of IM in the surface epithelium lining the nasal airways. No mucous cells or IM were present in the epithelia lining the nasal lateral meatus and maxillary sinus of rats exposed to 0 or 0.12 ppm ozone. In contrast, rats exposed to 0.5 or 1.0 ppm ozone had marked mucous cell metaplasia (MCM) with numerous mucous cells and conspicuous amounts of IM in the surface epithelium lining these upper airways. Ozone-induced increases in total epithelial cells (i.e., epithelial hyperplasia) were present only in rats exposed to 1.0 ppm. The results of this study indicate that rats chronically exposed to 1.0 or 0.5 ppm, but not 0. 121 ppm. ozone can develop marked MCM with significant increases in IM in both proximal and distal nasal airways. The epithelial chances observed throughout the nasal passages of ozone-exposed rats may be adaptive responses in an attempt to protect the upper and lower respiratory tract from further ozone-induced injury.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 603040
- Journal Information:
- American Journal of Respiratory Cell and Molecular Biology, Vol. 16; Other Information: PBD: 1997
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of 0. 12 and 0. 80 ppm ozone on rat nasal and nasopharyngeal epithelial mucosubstances: Quantitative histochemistry
Two-hour methyl isocyanate inhalation exposure and 91-day recovery: a preliminary description of pathologic changes in F344 rats