The skin is divided into three layers: Epidermis, Dermis and Subcutaneous tissue 0.3 layer total thickness of 1.25 mm, each layer to maintain the health of the skin has played an important role.
The dermis is located deep in the epidermis, down to the hypodermis, with no apparent boundary to the latter. The dermis consists of dense connective tissue. Its distribution of a variety of connective tissue cells and a large number of collagen fibers elastic fibers, the skin is both flexible, but also toughness. Connective tissue cells to fibroblasts and mast cells more. Different thickness of the dermis, palms, soles of the dermis thicker, about 3 mm above the eyelids, etc, the thinnest, about 0.6 mm. The general thickness of 1-2mm between. The dermis can be divided into papillary and reticular layers, located between the epidermis and subcutaneous tissue, mainly composed of connective tissue such as collagen fibers, elastic fibers, reticular fibers and amorphous matrix, among them there are nerve and nerve endings, blood vessels, lymph Tube, muscle and skin appendages.
The dermis can be divided into two layers, nipple layer and mesh layer. Nipple layer can be divided into dermal papilla and nipple (both collectively called the upper dermis). Mesh can also be divided into the middle of the dermis and the lower dermis, but there is no clear boundary between the two. Dermal connective tissue collagen fibers and elastic fibers intertwined with each other, buried in the matrix. Normal dermal cells with fibroblasts, tissue cells and mast cells. Collagen fibers, elastic fibers and matrix are secreted by fibroblasts. Reticular fibers are naive collagen fibers, not a separate component. The thickness of dermal tissue is closely related to the amount of fibrous tissue and matrix, and is closely related to the density, fullness, relaxation and wrinkling of the skin. In recent years, more and more dermatologists pay attention to the dermis.
Skin dermis layer structure
- Collagen fibers
It is the most abundant component of dermal connective tissue. Under the epidermis, the epidermal appendages and the collagen fibers near the blood vessels are small and not necessarily oriented. Collagen fibers in other parts of the dermis are combined into bundles. More fine in the upper part of the dermis, the more down the more coarse. In the middle and lower dermis, the collagen bundles are oriented almost parallel to the hide and intertwined with each other, extending in various directions on a horizontal plane. Collagen fiber is currently considered the most closely related to the aging of the dermal dermal components.
- Reticular fibers
Can be seen as a new slender collagen fibers. During the embryonic period, reticular fibers occur the earliest. In normal adult skin, reticular fibers are scarce, found only under the epidermis, sweat glands, sebaceous glands, hair follicles and capillaries. Subcutaneous mesh fibers arranged in a reticular. Around each fat there are mesh fibers around. In the wound healing or fibroblast proliferation of active lesions and the formation of new collagen, etc., reticular fibers can be a large number of hyperplasia.
- Elastic fibers
Smaller than collagen fibers, wavy. Elastic fibers in the dermis of the most thick, the arrangement of the same direction and collagen bundles, can be wound between the collagen bundles, parallel with the epidermis. In the subcutaneous epidermal papillary body, the tiny elastic fibers rose almost perpendicular to the epidermis, terminating in the dermis below the junction of the dermis. Elastic fibers and skin elasticity are closely related.
An amorphous material that fills the gap between collagen fibers and collagen bundles. Normal dermal matrix contains non-sulfate acid mucopolysaccharide, such as hyaluronic acid (also known as hyaluronic acid). In the normal skin content is very small, but because it can absorb 1000 times its water, so anti-wrinkle anti-aging skin is of great significance.
Dermis contains fibroblasts, mast cells, tissue cells, lymphocytes and a small amount of true bark dendritic cells, melanocytes, Langerhans cells. Fibroblasts can produce collagen fibers, elastic fibers, reticular fibers and matrix. At the same time in the deep dermal tissue damage is the main tissue repair cells.