Lotus lectin labels subpopulation of olfactory receptor cells

Experiments were performed to test the hypothesis that subsets of olfactory receptor cells could be recognized based on their lectin binding and that mapping of their projections onto the olfactory bulb would reveal details of anatomic organization of the olfactory nerve projection to the olfactory bulb. The results from one lectin, Lotus, were examined in detail. Olfactory receptor cells in the lateral part of the main epithelium were labeled, as well as scattered cells in the remainder of the epithelium. Glomeruli labeled by Lotus were concentrated primarily in the region of the olfactory bulb that receives its input from the lateral epithelium, although scattered glomeruli could be identified in other regions. Within the terminal field of these axons there was a mosaic pattern, with some glomeruli densely labeled, some lightly labeled and others unlabeled. These findings support the notion that there are biochemically distinct populations of olfactory receptor cells having localized distributions in the epithelium, with axons that coalesce to terminate in specific glomeruli, rather than diffusely over their projection field.