How does a gap junctions facilitate intercellular communication?

 

 
Gap junctions facilitate intercellular communication by allowing small signaling molecules to pass from cell to cell. These are fine hydrophilic channels between two adjacent animal cells that are formed with the help of two protein cylinders called connexus.
 
 
Each connexus consists of six proteins sub units that surround a hydrophilic channel. pH and Ca2+ ion concentration controls, opening or closing of channels.