IDENTIFICATION OF SURFACE GLYCOCONJUGATES IN THE OLFACTORY SYSTEM OF TURTLE

Lectin binding histochemistry was performed on the olfactory system of Pseudemys scripta to investigate the distribution and density of defi ned carbohydrate terminals on the cell surface glycoproteins of the ol factory receptors and their terminals in the olfactory bulbs. The lect in staining patterns indicate that the receptor cells of the olfactory mucosa are characterized by glycoconjugates containing alpha-D-galact ose and N-acetyl-D-glucosamine terminal residues. The vomeronasal rece ptor cells contain instead alpha-N-acetyl-D-galactosamine, N-acetyl-D- glucosamine and alpha-D-galactose residues. The results demonstrate th at the vomeronasal receptor cells contain high density of alpha-N-acet yl-D-galactosamine sugar residues that are not expressed by receptor c ells of the olfactory mucosa. The presence of specific might be relate d to the chemoreception and transduction of the glycoproteins, whose t erminal sugars are detected by lectin binding odorous message into a n ervous signal or in the histogenesis of the olfactory system. In fact, the olfactory receptors are the only known neurons in the vertebrate nervous system that undergo a continual cycle of proliferation not onl y in developing animals but also in mature ones. Moreover the results show that BSA-I-B-4, an alpha-D-galactosyl-specific isolectin, targets the terminal sugar residues in the ramified microglial cells.