[Gap junctions in sea anemone, Nematostella vectensis, embryo].

Gap junctions (GJs) are composed of membrane proteins that form channels connecting the cytoplasm of adjacent cells and permeable to ions and small molecules. They are considered to be the main or only type of intercellular channels and a universal feature of all multicellular animals (Metazoa). Till recently, sea anemones and corals (Anthozoa, Cnidaria) appeared to be an exception from this rule.