The dermis is one of the constitutive layers of the skin between the epidermis and subcutaneous tissues; it is composed of two layers, the papillary dermis lying immediately below the epidermis and the reticular dermis accounting for the largest part of the dermis. It is a 2 to 4 mm-thick layer of connective tissue mainly composed of extracellular matrix (ECM) produced by fibroblasts.
The dermis houses the neural, vascular, lymphatic systems, and epidermal appendages including excretory and secretory glands (sebaceous, eccrine and apocrine glands), hair follicles, and nails. Neural structures include sensory nerve receptors of Merkel and Meissner’s corpuscles (for touch), Pacinian corpuscles (for pressure), and Ruffini corpuscles (mechano-receptors). The dermis also hosts multifunctional cells of the immune system such as dendritic dermal cells, macrophages and mast cells .