Regional Differences in Proliferative Activity of Nasal Epithelium in Rat

ABSTRACT

We investigated the active proliferation sites of epithelial cells in normal nasal mucosa by immunohistochemical staining of proliferating cell nuclear antigen (PCNA), the marker of S phase of cell cycle and active cell proliferation. The whole nasal mucosa of the ten normal Sprague-Dawley rats were processed for PCNA immunolabeling. In respiratory portion, distinctly positive reaction was seen mainly in the anterior aspect, that is, the nuclei of squamous and non-ciliated cuboidal/transitional epithelium. These types of epithelial cells are transformed to pseudostratified ciliated epithelium in the posterior direction where positive reaction became scanty. In olfactory epithelium, the nuclei immunoreactive for PCNA were distinct in some area, but absent in other adjacent areas, lacking of region-specific immunolabeling that was observed in respiratory mucosa. These results suggest that anterior portion of nasal cavity is the main proliferation zone of normal nasal respiratory epithelium as well as the main site of protective function. In contrast, the neurogenesis of the olfactory nerve cells is not site-specific, indicating that any region covered by olfactory mucosa may be the main proliferation zone.