Which type of junction prevents diffusion between cells?

Occluding or tight junctions are specialized structures that form barriers between adjacent cells, preventing the movement of substances through the spaces between them. These junctions are composed of proteins that create a seal, effectively blocking the flow of ions, small molecules, and even larger substances, ensuring that materials must pass through the cells themselves rather than between them.

This characteristic is especially important in tissues that function as barriers, such as the epithelial layer of the intestines, where tight junctions help maintain distinct environments on either side of the cell layers. By contrast, gap junctions facilitate intercellular communication by allowing ions and small molecules to pass directly from one cell to another. Desmosomes and anchoring junctions primarily provide structural support and mechanical stability to tissues, allowing them to resist stress but do not serve the purpose of preventing diffusion.