Dense regular connective tissue is characterized by ordered and densely packed arrays of fibers and cells.
Dense regular connective tissue is the main functional component of tendons, ligaments, and aponeuroses. As in dense irregular connective tissue, the fibers of dense regular connective tissue are the prominent feature, and there is little ECM. However, in dense regular connective tissue, the fibers are arranged in parallel array and are densely packed to provide maximum strength. The cells that produce and maintain the fibers are packed and aligned between fiber bundles.
 Tendons are cordlike structures that attach muscle to bone. They consist of parallel bundles of collagen fibers.
Situated between these bundles are rows of fibroblasts called tendinocytes (Fig. 6.4 and Plate 5, page 194). Tendinocytes are surrounded by a specialized ECM that separates them from the load-bearing collagen fibrils. In H&E–stained cross sections of tendon, the tendinocytes appear stellate. In transmission electron micrograph (TEM) sections parallel to the long axis of tendons, the cytoplasmic projections of the cell are seen to lie be tween the fibers and appear as thin cytoplasmic sheets. In most H&E–stained longitudinal sections, however, tendinocytes appear only as rows of typically flattened basophilic nuclei. The cytoplasmic sheets that extend from the body of the tendinocytes are not usually evident in longitudinal H&E–stained sections because they blend in with the collagen fibers. The substance of the tendon is surrounded by a thin connective tissue capsule, the epitendineum, in which the collagen fibers are not nearly as orderly (Plate 5, page 194). Typically, the tendon is subdivided into fascicles by endotendineum, a connective tissue extension of the epitendineum. It contains the small blood vessels and nerves of the tendon.
 Ligaments, like tendons, consist of fibers and fibroblasts arranged in parallel. The fibers of ligaments, however, are less regularly arranged than those of tendons. Ligaments join bone to bone, which in some locations, such as in the spinal column, requires some elasticity. Although collagen is the major extracellular fiber of most ligaments, some of the ligaments associated with the spinal column (e.g., ligamenta flava) contain many more elastic fibers and fewer collagen fibers. These ligaments are called elastic ligaments.
 Aponeuroses resemble broad, flattened tendons. Instead of fibers lying in parallel arrays, the fibers of aponeuroses are arranged in multiple layers. The bundles of collagen fibers in one layer tend to be arranged at a 90 angle to those in the neighboring layers. The fibers within each of the layers are arranged in regular arrays; thus, aponeurosis is a dense regular connective tissue. This orthogonal array is also found in the cornea of the eye and is responsible for its transparency.
Connective tissue fibers are of three principal types.
Connective tissue fibers are present in varying amounts, depending on the structural needs or function of the connective tissue. Each type of fiber is produced by fibroblasts and is composed of protein consisting of long peptide chains. The types of connective tissue fibers are
Collagen fibers are the most abundant type of connective tissue fiber.
Collagen fbers are the most abundant structural components of the connective tissue. They are flexible and have a