How cells use condensation to seal tissues tight

Our bodies and organs are shielded from the external environment by tissue barriers like the skin. These barriers must be tightly sealed to prevent unwanted substances from entering. This sealing is achieved through structures called tight junctions. However, how these tight junctions form has long been a mystery. Now, biologists have uncovered that the proteins responsible for these seals form a liquid-like material on the cell surface much like the water that condenses on a cold window.