Dense regular connective tissue
Textus connectivus densus regularis
Also known as: tendon tissue, ligament tissue, aponeurosis
Tightly packed, parallel bundles of type I collagen with rows of flattened fibroblasts, giving great tensile strength in one direction; forms tendons, most ligaments and aponeuroses.
Overview
Thick type I collagen fibres are aligned parallel to the direction of pull, with rows of elongated fibroblasts (tenocytes in tendons) squeezed between them; ground substance and cells are sparse. In tendons, collagen fibrils are grouped into fibres, fascicles (bounded by endotenon) and the whole tendon (surrounded by epitenon). The undulating "crimp" of relaxed collagen straightens under initial loading, giving some give before the fibres bear full tension.
The tissue resists very high tensile loads along its long axis but is weak against forces from other directions. It is poorly vascularised, so injuries heal slowly and often incompletely, by scar tissue with less organised collagen. A specialised form makes up the stroma of the cornea, where layers of regularly spaced parallel collagen lamellae alternate in direction and transparency results from their uniform spacing.
- Location
Tendons, most ligaments, aponeuroses, some fasciae, corneal stroma.
Anatomy
- Histology
Parallel, wavy, eosinophilic collagen bundles with rows of flat, dark fibroblast nuclei between them.
Function
- Transmits muscle force to bone (tendons).
- Binds bones together and limits joint movement (ligaments).
Clinical significance
Tendon and ligament injury
Sprains (ligament) and strains (tendon/muscle) heal slowly because of the poor blood supply. Tendinopathy and rupture of the calcaneal (Achilles) tendon are associated with fluoroquinolone antibiotics and corticosteroid injection.
Compiled from standard anatomy and physiology references — see the Cells & Tissues sources. For education only; not medical advice.