Tendon
In dense regular connective tissue the bundles of collagen are all parallel to each other. The bar in this image shows you the width of this piece of dense regular connective tissue, which comes from a tendon.
Tendon
The collagen fibers are parallel to the arrow bar. Some of the dark spots you can see on this image are the nuclei of the fibroblasts that make the collagen fibers.
Tendon
In this image a fibroblast nucleus (fb nuc) is labeled, but you can see other nuclei once you know what to look for. You can't see the rest of the fibroblast cell because it stains the same color as the collagen fibers. The collagen fibers (cf) are parallel to the arrow bar. It's hard to see on the image, but the collagen fibers are not really straight. They have a slight "wave".
The "art" label indicates an artifact--a place where the collagen fibers pulled apart slightly during processing. Don't confuse the artifacts with real structures.