Gap junctions, electrotonic coupling, and intercellular communication

This Bulletin treats first the structural characteristics of gap junctions. Then, the roles and distribution of electronic coupling in excitable tissues are considered. In assaying the possible nonelectric roles of gap junctions, their permeability is reviewed. The question of how gap junctions might operate in development is analyzed in respect to the nature of the signaling process about which more is known than about the actual pathway utilized. Finally, the control of the incidence of gap junctions is discussed. The processes of formation and dissolution of the junctions and the specification of the cell types involved all must ultimately be analyzed for an adequate gasp of the functions of this ubiquitous organelle.