Final answer:
Tight junctions are composed of proteins called claudins and occludins that create a watertight seal between adjacent animal cells, preventing material leakage and maintaining tissue integrity.
Step-by-step explanation:
The major structural components of tight junctions are proteins that create a watertight barrier between adjacent animal cells. These proteins prevent materials from leaking between the cells and are crucial in maintaining the integrity of epithelial tissues which line internal organs and cavities and are also a major part of the skin. The proteins predominantly responsible for this seal are called claudins and occludins, which hold the cells firmly against each other, ensuring the tight adhesion characteristic of tight junctions.