HISTOCHEMICAL-STUDY BY LECTIN-BINDING OF SURFACE GLYCOCONJUGATES IN THE DEVELOPING OLFACTORY SYSTEM OF RAT

Lectin-binding histochemistry was used to investigate the distribution and density of defined carbohydrate sequences on the cell surface gly coproteins of the olfactory receptors of rat during development. The o lfactory and vomeronasal receptors showed a positive labelling after b iotinylated Lycopersicum esculentum lectin binding on embryonic day 16 (E16), while horseradish peroxidase-labelled Glycine max, Bandeiraea simplicifolia (BSA-I) and its B-4 isomer BSA-I-B-4 agglutinins started to label from day is (Els). From this stage onward there was a progre ssive increase in the intensity and number of lectin-binding olfactory receptors. The first lectin-labelled bundles of axons penetrating the olfactory bulb were observed on E20; from E21 it was possible to iden tify the first labelled glomeruli that, on the first day (PZ) of postn atal life, showed a feature very similar to that of the adult. The lec tin staining patterns indicate that during development there are diffe rences in the kind and distribution of saccharidic moieties on the sur face of rat olfactory neurons. The possible role of carbohydrate-conta ining glycoproteins in the reception and transduction of the odours an d in the modulation of the cell-cell interactions in the olfactory sys tem is discussed.