There is increasing evidence that lectins are widely distributed in ma
mmalian tissues, including the nervous tissue. Based on histochemical
techniques using neoglycoproteins, different lectin activities specifi
c for different monosaccharides or glycans have been identified (fucos
e, galactose, mannose, N-acetylglucosamine, N-acetylgalactosamine, N-a
cetylneuraminic acid and heparin). Most of them showed a cellular spec
ificity and developmental regulation in the central nervous system. Se
veral lectins isolated from the nervous tissue seem to play an essenti
al role during ontogenetic processes, especially as far as cell adhesi
on and cell recognition mechanisms are concerned (axonal growth and fa
sciculation, neuron migration, synaptogenesis, myelination). But some
of them seem to be involved in signaling events both intracellularly (
nuclear lectins) or at the cell surface by autocrine and paracrine mec
hanisms. This review discusses the structure and the identified functi
ons of these important constituents of the nervous tissue.