Morphology and intercellular communication in glial cells of intramural ganglia from the guinea-pig urinary bladder

Neurons in most peripheral ganglia are surrounded by satellite glial cells (SCs), but these cells have so far received little attention. We used immun ohistochemistry and intracellular injections of tracers to characterize SCs in the intramural ganglia of the guinea-pig urinary bladder, which are par t of the parasympathetic system. Intracellular injections of horseradish pe roxidase (HRP) revealed two morphological types: cells that surrounded neur ons and are SCs proper, and bipolar cells with processes that projected int o the nerve fiber bundles connecting the ganglia. SCs were immunopositive f or glutamine synthetase (GS) and S100 beta and immunonegative for glial fib rillary acidic protein (GFAP). Injections of Lucifer yellow (LY) or biocyti n (molecules known to cross gap junctions) into single SCs showed that thes e cells have a very low degree of intercellular coupling. A mean of 0.31 an d 0.71 cells were coupled to the injected cells, using LY and biocytin, res pectively. It appears that SCs in the bladder ganglia are distinct from cen tral and enteric glial cells in the small degree of their coupling and in t he absence of GFAP immunostaining. (C) 1999 Elsevier Science B.V. All right s reserved.