Regeneration of skin appendages and nerves: current status and further challenges

Table 1 The structure of human skin and their functions

	Locations	Functions	References
Epidermis
Melanocytes	Stratum basale	Production of melanosomes	[2]
Merkel cells	Stratum basale	Sensor	[2]
Keratinocytes	Stratum corneum Basement membrane	Secrete lipids, protease inhibitors, hydrolases, and antimicrobial peptides	[1, 2]
Langerhans cells	Stratum spinosum	Serving an immunologic role	[2]
Dermoepidermal junction	Epidermal and dermal layers	Regulates adhesion, movement, and growth of keratinocytes and fibroblasts4 Provides structural support for epidermis	[2]
Dermis
Vasculature	Superficial plexus: papillary and reticular dermis Deep plexus: reticular dermis and hypodermis	Supply oxygen and nutrients to skin
Arrector pili muscle	Attach to the hair follicle below the sebaceous glands	Pull the hair follicle	[2]
Arteries smooth muscle	Arterial wall	Perfusion blood
Skeletal muscle	Face and anterolateral neck	Facilitate facial expression
Nerves	Along arterioles and venules	Touch, pressure, temperature, itch, and pain sensation	[106]
Skin appendages
Hair Follicle	Dermal layer of the skin	Form physical barrier, antibacterial, inhibit scar formation	[28]
Eccrine sweat glands	Palms and soles	Regulate body temperature	[61]
Apocrine sweat glands	Axillary and anogenital regions	Cause the characteristic smell of body	[61]
Sebaceous glands	Hair follicle and the arrector pili muscle	Secrete sebum and lubricate, protect against microorganisms	[78,79,80]
Hypodermis	Beneath the dermis and above the muscle	Insulate from the cold and violent trauma, provides buoyancy, storing energy	[2]

ISSN: 1479-5876