Table 1.

Constituents and functions of the layers of skin.

	Locations	Functions
Epidermis
Keratinocytes	Full layer of epidermis	Synthetic keratin, constitutes the skin barrier
Melanocytes	Stratum basale	Production of melanosomes
Merkel cells	Stratum basale	Sensor
Langerhans cells	Stratum spinosum	Antigen-presenting cells, serving an immunologic role
Laminin	Basement membrane	Connect dermis and epidermis
Dermis
Fibroblasts	Full layer of dermis	Synthesize ECM, secrete various cytokines, and promote wound repair
Collagen fibers	Full layer of dermis	Supporting and protecting function
Elastic fibers	The reticular dermis	Skin elasticity
Blood vessels	The papillary dermis	Supply oxygen and nutrients to skin
Nerves	Along arterioles and venules	Touch, pressure, temperature, itch, and pain sensation
Sweat glands	The reticular dermis	Regulate body temperature
Hair follicle	The reticular dermis	Form physical barrier, antibacterial, inhibit scar formation
Hypodermis
Adipocytes	Beneath the dermis and above the muscle	Insulate from the cold and violent trauma, provides buoyancy, storing energy
Fibroblasts	Hypodermis	Synthesize ECM, secrete various cytokines, and promote wound repair
Macrophages	Hypodermis	Phagocytosis, adaptive immunity, wound healing