IN-VITRO CHANGES OF GANGLIOSIDE IMMUNOSTAIN LOCALIZATION IN DEVELOPING NEURAL CELLS

The immunostains of GD3, c-pathway polysialogangliosides and gangliotetraosylgangliosides belonging to the a- and b-pathways were analyzed in embryo optic lobe cells. Cells were cultured in serum free media with, and without, bovine brain ganglioside mixture (largely gangliotetraosylgangliosides). Control cells differentiated in vitro, whereas ganglioside treated cells emitted almost no neurites. In immature cells, GD3 and c-gangliosides were extensively expressed and their immunostains were observed all over the cell (general localization), whereas gangliotetraosylgangliosides were scanty and their stain was preferentially restricted to discrete areas (in clusters). In control differentiated cells, the GD3 expression was strikingly reduced and its immunostain appeared in clusters; c-gangliosides were abundant and their stain was found with general localization; the expression of gangliotetraosylgangliosides became important and their stain was observed with general localization in most of the positive cells. In ganglioside treated cells, in spite of their undifferentiated morphology, the gangliotetraosylganglioside stain appeared with general localization. These results suggest that gangliosides involved in neural ontogenesis are preferentially located in clusters when they are scarce and have general localization when they are abundant in membranes.