Figure 1.

Skin structure and healing process. (A) The structure of the skin consists of three parts: the epidermis, the dermis, and the hypodermis. The epidermis is an important protective layer of skin, mainly consisting of keratinocytes and non-keratinocytes. Non-keratinocytes mainly include Langerhans cells and melanocytes, while keratinocytes are the main cells that make up the structure of each layer. The dermis, which consists of dense connective tissue, lies beneath the epidermis and is mainly composed of fibroblasts, collagen, and various immune cells. The dermis is the primary site within the skin where immune responses occur and where skin density and firmness are maintained. The hypodermis consists of loose connective tissue and fat cells that lie beneath the dermis, maintaining body temperature and cushioning pressure. (B) The process of wound healing can be divided into four periods: hemostasis, inflammation, proliferation, and tissue remodeling. Multiple cell types, including endothelial cells, keratinocytes, fibroblasts, and various immune cells, work together to coordinate the skin wound healing process.