Lectin binding sites in the vomeronasal organ and the olfactory epithelium of the tree shrew tupaia belangeri.

Abstract

Lectin binding histochemistry was performed on the peripheral parts of the vomeronasal and olfactory system of Tupaia belangeri to investigate the distribution and density of defined carbohydrate terminals on the cell surface glycoproteins of the specific receptors, nerves and associated glands. Dolichus biflorus lectin staining was identifiable in all cells of the sensory epithelia of both systems, with the exception of the olfactory basal cells. The vomeronasal nerve expressed alpha-N-acetylgalactosamine, the olfactory nerve did not. Differences in the Dolichus biflorus lectin staining pattern were noted in the sensory and the non-sensory epithelium of the vomeronasal organ of pregnant and non-pregnant Tupaia belangeri. Like in other mammals examined so far, the systems were characterized by a moderate to high alpha-fucose density, only the supporting cells of the olfactory epithelium remaining unstained by Ulex europaeus I lectin. Bandeiraea simplicifolia II lectin binding was moderate in the olfactory glands and the brush border. In the vomeronasal organ, sugar residues of alpha- and beta-N-acetyl-D-glucosamine were found selectively in the transition zone between the two vomeronasal epithelia, where regeneration should take place. We tentatively conclude that specific glycoproteins, whose terminal sugars were detected by lectin binding, might be related to the chemoreception and transduction of the olfactory/pheromonal message into a nervous signal or to the histogenesis of the olfactory/vomeronasal system. This study showed that beside the species, pregnancy might play a role in these processes in the vomeronasal organ.