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.