Expression of intermediate filaments and desmoplakin in vertebrate olfactory mucosa.

The expression of intermediate filaments (IF) and desmoplakin was investigated in frog, bovine, and human (fetal) olfactory mucosa. IF are tissue-specific molecular cytoskeletal markers; desmoplakin is the major desmosomal protein. Positive immunoreactivity was observed in the epithelium and in the subepithelial Bowman's glands to keratin and to desmoplakin, indicating the epithelial nature of this tissue. Desmin, neurofilaments, and glial fibrillary acidic protein (GFAP) were not detected in the mucosa. The absence of neurofilaments and GFAP in the tissue containing sensory neurons and glia-like supporting cells is a unique feature and may be related to the fact that the chemosensory neurons are situated in a bonafide epithelium and are known to undergo continuous turnover. In view of the controversy regarding the expression of vimentin in the olfactory neurons, three independently derived antibodies to vimentin were used; weak or no labeling was found in the epithelium, whereas mesenchymal cells in the lamina propia were labeled with all three antibodies. Olfactory nerve fascicles in the lamina propia were heterogenously labeled: VIM 13.2 gave very weak labeling; aVimAS showed mild labeling and SBV-21 showed intensive labeling in the nerve fascicle. This heterogenous labeling pattern may suggest that olfactory vimentin is distinct in reacting only with some of the antivimentin antibodies.