The Zonula Occludens, also known as tight junctions, are specialized structures found between epithelial cells. They play a crucial role in maintaining the integrity of cell layers by preventing the passage of substances between cells, thus controlling what enters and exits tissues. This function is essential for maintaining a barrier in organs such as the intestines and blood-brain barrier. These junctions are composed of various proteins that link adjacent cells together, forming a seal. By regulating permeability, the Zonula Occludens helps protect underlying tissues from harmful substances and pathogens, ensuring proper physiological function and homeostasis.