Cell surface glycoconjugates in the olfactory system of lungfish Protopterus annectens Owen

Lectin binding was performed on the olfactory system of lungfish Protopteru s annectens to identify specific glycoconjugates on the cell surface of olf actory receptor cells. The lectin histochemical patterns and the Western bl ot analysis indicate that the receptor cells of the olfactory mucosa are ch aracterized by high density of alpha-N-acetyl-D-galactosamine residues on t he saccharidic chains of the surface glycoproteins. Other lectins display a regional pattern between the regions of the olfactory bulbs. This differen t histochemical lectin pattern might be due to a different regional segrega tion of the olfactory projections. On the other hand it could allow the ide ntification of an area corresponding to the accessory olfactory bulb of ter restrial vertebrates in the ventrolateral region of Protopterus olfactory b ulb. The presence in the dipnoan olfactory system of a vomeronasal organ ho mologous to the organ in amphibians is discussed. Moreover, the selective l ectin binding on the surface of primary olfactory neurones suggests that sp ecific cell surface glycoproteins may have a role in the axonal growth due to the continuous cycle of proliferation and the death of olfactory recepto r cells.