The dermis contains tear-resistant collagen fibers and elastic fibers . In addition, numerous blood and lymph vessels are woven into the dermis. The skin glands and hair roots are mainly located within the dermis and most of the skin's sensory receptors are also located in this layer.
The elastic fibers are responsible for the suppleness and adaptability of the skin. This elasticity decreases significantly with age. In addition, the tension in the fiber bundles causes the wound edges to gape apart if the skin is injured.
The main direction of the collagen fiber bundles is designated by the term skin split lines , also called Langer lines after the Austrian anatomist Karl Langer von Edenberg . Wounds in the direction of the cleavage lines gape less than transverse ones. Surgeons try to take advantage of this fact by placing incisions along the cleavage lines.
Papillary layer, stratum papillare
The tissue rich in capillaries , which is most developed in adolescence, also causes the folding of the dermal-epidermal transition zone (DE junction). The transition zone is used mechanically to better fix the two layers. In the case of venous return flow defects, enlarged veins, so-called spider veins, appear.
Most of the skin's sensory cells are also located in the stratum papillare. The intercellular spaces are wide and filled with a jelly-like fluid ( interstitium ), which is drained through the lymphatic system beginning here . Different cells can move fairly freely in this tissue. Defense cells, such as macrophages , lymphocytes , plasma cells , mast cells , granulocytes and monocytes, but also cells that form connective tissue ( fibroblasts ) can be found.
Between the dermis and the epidermis there is a wave-like to cone-shaped border, the so-called papillary body . The multiple invaginations of the dermis in the underside of the epidermis result in a large surface and thus a firm mechanical connection between the two layers and an easier delivery of nutrients to the epidermis.
The papillary body has relatively flat papillae in hairy areas of skin, since the hair also helps to anchor the epidermis.
Reticular layer, stratum reticulare / texticulare
In the stratum reticulare (Latin for 'network layer', syn. Stratum texticulare ) there is tight, braided connective tissue with collagen fibers (type I) and accompanying elastic fibers. The amount of fluid in this layer determines the firmness of the skin.
- Peter Schulze (Ed.): Anatomical Dictionary: Latin-German, German-Latin . 7th edition. Georg Thieme Verlag , Stuttgart, New York 2001, p. 31 .