ELECTRON CYTOCHEMICAL STUDY OF CARBOHYDRATE COMPONENTS IN DIFFERENT TYPES OF CULTURED GLIAL-CELLS OF SNAIL HELIX-POMATIA

Using a variety of colloidal gold-labelled lectins with different suga r specificities, the structure and topography of carbohydrate determin ants of the surface membrane of in vitro cultured glial and nerve cell s of the snail Helix pomatia have been electron cytochemically studied . Heterogeneity of carbohydrate pools among different types of glial c ells and between glial and nerve cells was established. It was found t hat satellite glial cells having the ultrastructural signs of cells wi th high metabolic level (type II cells) selectively bind GNA which is specific to terminal alpha-D-mannose residues and do not bind other ma nnose-specific lectins, Con A and LCA. GNA determinants are absent in satellite type I glial cells, fibrous glial cells, microglia and neuro ns. It has been found that glial cells (satellite type I and II glial cells, filamentous glial cells and microglial cells) do not bind PVA a nd LABA. LTA did not bind to any glial cells and binds weakly to neuro ns. Con A and WGA determinants which are abundant on the neurons are c ompletely absent on satellite type II glial cells but present on satel lite type I glial cells and filamentous glial cells. Microglial cells contain Con A and LCA determinants and the density of PNA determinants on these cells is the highest compared to other types of glial cells or neurons. It is concluded that some lectin determinants (for RCA-1, PNA, LPA) are present on all types of glial cells, while another deter minant (GNA) is specific for a definite type of glial cells and can se rv as a marker of these cells. The role of specific carbohydrate deter minants in the functioning of a neuron-glial complex is discussed.