In the special senses, some epithelia act as receptors in a sensory capacity.
Most epithelia possess common characteristics that contribute to their functional capabilities.
Limited intercellular space - specialized intercellular junctions hold the membranes of epithelial cells tightly together. This results in restricted intercellular space between cells. The junctions can enable epithelial cells to form effective barriers even though some are but a single layer in thickness. This enables epithelial cells to control substances that pass from one side of the cell to the other. In this way epithelia serve in absorptive, secretory, and excretory functions.