Merkel cell
Encyclopedia
Merkel cells or Merkel-Ranvier cells are oval receptor cells found in the skin of vertebrates that have synaptic contacts with somatosensory afferent
s. They are associated with the sense of light touch discrimination of shapes and textures. They can turn malignant and form the skin tumor known as Merkel cell carcinoma
.
There is evidence that they are derived from neural crest
. More recent experiments in mammals have indicated that they are in fact epithelial in origin.
derived, but experiments in mammals now demonstrate an epidermal origin.
Afferent
Afferent is an anatomical term with the following meanings:*Conveying towards a center, for example the afferent arterioles conveying blood towards the Bowman's capsule in the Kidney. Opposite to Efferent.*Something that so conducts, see Afferent nerve fiber...
s. They are associated with the sense of light touch discrimination of shapes and textures. They can turn malignant and form the skin tumor known as Merkel cell carcinoma
Merkel cell carcinoma
Merkel cell carcinoma Merkel cell carcinoma Merkel cell carcinoma (also known as a "Cutaneous apudoma," "Primary neuroendocrine carcinoma of the skin," "Primary small cell carcinoma of the skin," and "Trabecular carcinoma of the skin"...
.
There is evidence that they are derived from neural crest
Neural crest
Neural crest cells are a transient, multipotent, migratory cell population unique to vertebrates that gives rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia....
. More recent experiments in mammals have indicated that they are in fact epithelial in origin.
Location
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.Function
Friedrich S. 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 because they contain dense core granules, and thus may also have a neuroendocrine function.Developmental origin
The origin of Merkel cells has been debated for over 20 years. Evidence from skin graft experiments in birds implies that they are neural crestNeural crest
Neural crest cells are a transient, multipotent, migratory cell population unique to vertebrates that gives rise to a diverse cell lineage including melanocytes, craniofacial cartilage and bone, smooth muscle, peripheral and enteric neurons and glia....
derived, but experiments in mammals now demonstrate an epidermal origin.
External links
- NIF Search - Merckel Disc Cell via the Neuroscience Information FrameworkNeuroscience Information FrameworkThe Neuroscience Information Framework is a repository of global neuroscience web resources, including experimental, clinical, and translational neuroscience databases, knowledge bases, atlases, and genetic/genomic resources.-Description:...