Tight junction

Tight junctions, also known as occluding junctions or zonulae occludentes (singular, zonula occludens), are multiprotein junctional complexes between epithelial cells,^[1] sealing and preventing leakage of solutes and water. They also play a critical role maintaining the structure and permeability of endothelial cells.^[1] Tight junctions may also serve as leaky pathways by forming selective channels for small cations, anions, or water. The corresponding junctions that occur in invertebrates are septate junctions.