Intercellular Contacts Specialized cell contacts are an extremely remarkable feature of animal cells. Tight junctions prevent leakage through tissues. It would definitely not be a good idea to have your gut contents leaking into your abdomen. Adhering junctions hold adjacent cells together and stabilize tissues. These are found in many tissues, and are particularly abundant in human skin, providing us with a nice strong outer covering.
Gap junctions are open pathways between the cytoplasm of two adjacent cells.
Substances with a molecular weight of 1200 daltons or lower can move directly from one cell to another via gap junctions. Gap junctions are found in many tissues, including the heart, and are extremely abundant in embryos. The function of embryonic gap junctions is not fully understood, but normal develop cannot occur if they are blocked. An extracellular matrix of proteins and sugars surrounds most cells in an animal's body. The fact that its basic elements are the same in all animals provides strong additional support to the idea that the animals have a single evolutionary origin.