[The variability of the surface morphology of olfactory sensory receptors]

The olfactory epithelium of the adult hamster (mesocricetus auratus) was examined by light- and scanning electron microscopy. Tissues were perfusion-fixed in buffered glutaraldehyde solution. Of particular interest were the regionally varying, thickly structured olfactory boarder and the polymorphic olfactory receptors. The forms varied from simple, smooth olfactory vesicles to highly differentiated receptors with up to 20 cilia of varying length per vesicle. The cilia were tapered at such a rate that the distal segments had an average diameter 1/2 to 1/3 of the proximal segment. The distal segments were arranged in a parallel fashion occasionally over more than 100 microns in length between the surface of the epithelium and the loose meshlike plexus of the olfactory border. A second receptor type was also frequently observed in which the surface area was increased through microvilli. These variations in the structure of the receptors are discussed with regard to new immunohistochemical results. Further experiments should determine the relationship of local morphological differences.