Dye coupling among glial cells in the ganglia of the myenteric and submucosal plexuses of the guinea-pig ileum was studied by intracellular injection of the dye Lucifer yellow (LY), which crosses gap junctions. The injection of a single glial cell with LY resulted in the staining of many glia. The mean number of cells coupled to the injected one was 87.0 +/- 7.9 in the myenteric plexus, and 20.7 +/- 5.6 in the submucosal plexus. As previously shown for myenteric plexus, injection of horseradish peroxidase into submucosal glia resulted in the staining of only a single cell. Dye coupling was significantly reduced in both plexuses by lowering intracellular pH, by replacing 100 mM of the chloride ions with propionate ions or by bubbling the solution with 100% CO2. Octanol (0.3 mM) also markedly diminished dye coupling in the two preparations. These treatments are known to block gap junctions in a variety of tissues. It is concluded that, like central glial cells, enteric glia are extensively coupled. This coupling is apparently mediated by gap junctions.