Talk about gap junctions.

Pipline structures occurring between neighboring cells in clusters, made of integral proteins, named connexins, play a role in transportation and molecule exchange. Occur in nearly all tissues except skeletal and nervous ones (AP Ca dependent). Present in cardiac muscle and mediate rapid propagation which ensures synchronization of movement of all cells making them as if one cell with multiple nuclei. In smooth muscles (esophagus), ions propagating causes contractions that enable swallowing (peristaltic movement)