Merkel cell

Merkel cell
Merkel cells (shown in blue) are located in the basal epidermal layer of the skin.
Identifiers
NeuroLex ID	Merckel disc cell
Anatomical terminology []

Merkel cells, also known as Merkel-Ranvier cells or tactile epithelial cells, are oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of vertebrates. They are abundant in highly sensitive skin like that of the fingertips in humans, and make synaptic contacts with somatosensory afferent nerve fibers. Although uncommon, these cells may become malignant and form a Merkel cell carcinoma—an aggressive and difficult to treat skin cancer.

Although it has been reported that Merkel cells are derived from neural crest cells, more recent experiments in mammals have indicated that they are in fact epithelial in origin.

Merkel cells are found in the skin and some parts of the mucosa of all vertebrates. In mammalian skin, they are clear cells found in the stratum basale (at the bottom of sweat duct ridges) of the epidermis approximately 10 µm in diameter. They also occur in epidermal invaginations of the plantar foot surface called rete ridges. Most often, they are associated with sensory nerve endings, when they are known as Merkel nerve endings (also called a Merkel cell-neurite complex). They are associated with slowly adapting (SA1) somatosensory nerve fibers.

Friedrich Sigmund Merkel referred to these cells as Tastzellen or "touch cells" but this proposed function has been controversial as it has been hard to prove. However, genetic knockout mice have recently shown that Merkel cells are essential for the specialized coding by which afferent nerves resolve fine spatial details. Merkel cells are sometimes considered APUD cells (an older definition. More commonly classified as a part of dispersed neuroendocrine system) because they contain dense core granules, and thus may also have a neuroendocrine function.