The dominant type of fiber in dense connective tissue is collagen, as explained by McGraw-Hill Higher Education. Dense connective tissues may also contain elastic protein fibers or reticular fibers, according to the University of Western Australia.
The University of Western Australia also explains that the collagen fibers are composed of smaller units. Tropocollagen is formed by three collagen molecules in the form of a triple helix. Tropocollagen subunits form collagen microfibrils, which then form thin collagen fibrils. Collagen fibrils, in turn, compose collagen fibers.
According to Yale University, dense connective tissue can be found in walls of arteries, bone, tendon and the dermal layer of the skin.