What Is the Papillary Dermis?
The skin is covered on the body surface, and from the outside to the inside it is the epidermis, dermis, and subcutaneous layer. The dermis is differentiated from the mesoderm, divided into two layers, the papillary layer and the reticular layer. There is no obvious boundary between the two. Numerous nipples protruding from the dermis are embedded in the deep side of the epidermis. The deep side of the dermis is connected to the superficial fascia by connective tissue fiber bundles. The dermis is generally 1 to 2 mm thick.
- Foreign name
- Dermis
- Make up
- The main ingredient is collagen fibers
- Function
- Skin immune response
- The skin is covered on the body surface, and from the outside to the inside it is the epidermis, dermis, and subcutaneous layer. The dermis is differentiated from the mesoderm, divided into two layers, the papillary layer and the reticular layer. There is no obvious boundary between the two. Numerous nipples protruding from the dermis are embedded in the deep side of the epidermis. The deep side of the dermis is connected to the superficial fascia by connective tissue fiber bundles. The dermis is generally 1 to 2 mm thick.
Dermis composition
- The dermis is mainly composed of fibroblasts and the fibers and stroma they produce, and has blood vessels, lymphatic vessels, nerves, skin appendages, and other cellular components.
1. Fibers (1) Collagen fibers: It is the main component of dermal fibers. It is made by polymerizing collagen fibrils with a diameter of 70 to 140 nm, and its diameter is 2 to 15 m, which are mostly bundles.
(2) Reticulated fibers: immature, slender immature collagen fibers with a diameter of 0.2 to 1.0 m, which are only found under the epidermis, sebaceous glands, capillaries, hair follicles, and sweat glands.
(3) Elastic fiber: It consists of microfibrils and elastin, with a diameter of 1 ~ 3m, and it is in a thin bundle. It is intertwined with collagen fibers.
2. The matrix is composed of a complex composed of mucopolysaccharides and proteins such as hyaluronic acid, chondroitin sulfate, that is, proteoglycans, which are filled in the gaps between collagen fibers and fiber bundles and between cells, and are hydrophilic.
3. The cells are mainly fibroblasts, followed by mast cells, macrophages, dendritic cells, Langerhans cells and phagocytic cells, and a small number of lymphocytes and leukocytes.
Dermal effect
- The skin's immune response mainly occurs in the dermis, where mast cells, macrophages, dendritic cells and other interactions in the superficial layer of the dermis interact with each other through their synthetic cytokines to activate, migrate, and proliferate immune cells. Induction of immune response, inflammatory injury and wound repair all play important roles. It can also cause inflammation and hypersensitivity when bacteria invade.
Dermal histopathological changes
- 1. Blood circulation and lymphatic circulation disorders include vasodilation and congestion, dermal edema, bleeding, vascular lumen occlusion and embolism, and lymphatic circulation disorders.
2. Degeneration includes dermal degeneration, hyaline degeneration, fibrinoid degeneration, amyloid degeneration, gelatinous degeneration and elastic fibrosis, eosinophilic degeneration, mucus degeneration, collagen dissolution, pigmentation, lipid deposition, calcium deposition, etc.
3. Common types of necrosis include caseous necrosis, liquefied necrosis, and progressive necrosis.
4. Other apoptosis, inflammation, granulation tissue and granuloma, connective tissue hyperplasia and sclerosis.