Dermis

The dermis is the thick, vascularized connective tissue layer of the skin that lies beneath the epidermis and above the subcutaneous tissue. It provides mechanical strength and elasticity to the skin through a matrix of collagen and elastin fibers. The dermis is classically divided into two layers: the superficial papillary dermis and the deeper reticular dermis, each with distinct structures and functions.

The papillary dermis lies just beneath the epidermis and is composed of loose connective tissue. It contains dermal papillae that project into the epidermis, forming structures such as fingerprints. This layer houses capillary loops that nourish the epidermis and contains sensory receptors, including Meissner corpuscles for light touch and free nerve endings for pain and temperature sensation. The reticular dermis is thicker and made of dense irregular connective tissue rich in collagen bundles and elastin, which provide strength and stretch. It hosts hair follicles, sebaceous glands, and sweat glands, as well as larger blood vessels, lymphatics, and deeper neural receptors such as Pacinian and Ruffini endings.

Functions of the dermis include supplying nutrients to the epidermis via its vascular network, regulating temperature through sweat production and blood flow, and mediating sensation and proprioception through various cutaneous receptors. It also supports hair growth and plays a central role in wound healing, with fibroblasts synthesizing collagen and other extracellular matrix components during repair.

Clinical aspects include age-related changes in collagen and elastin that affect skin elasticity, regional variations in dermal thickness, and the dermis’s involvement in scarring and scar remodeling after injury.