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Merkel cells

Wednesday 5 May 2004

Definition: Merkel cells are oval receptor cells found in the skin of vertebrates that have synaptic contacts with somatosensory afferents. 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.

Images

- Merkel discs / Merckel cells

History

Merkel cells were given their name in 1878 by Robert Bonnet after the 19th century German anatomist Friedrich Sigmund Merkel who was the first to fully describe them in 1875.

Location

Merkel cells are found in the skin and some parts of the mucosa (stratum germinativum) 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 crest derived, but experiments in mammals now demonstrate an epidermal origin.

Pathology

- Merkel cell carcinoma

References

- Merkel’s cells Who named it

- Merkel FS. (1875). Tastzellen und Tastkörperchen bei den Hausthieren und beim Menschen. Archiv für mikroskopische Anatomie, 11: 636-652.

- Halata Z, Grim M, Bauman KI. (2003). Friedrich Sigmund Merkel and his "Merkel cell", morphology, development, and physiology: review and new results. Anat Rec A Discov Mol Cell Evol Biol. 271(1):225-39. PMID 12552639

- Maricich SM, Wellnitz SA, Nelson AM, Lesniak DR, Gerling GJ, Lumpkin EA, Zoghbi HY. (2009). Merkel Cells Are Essential for Light-Touch Responses. 324: 1580 - 1582. doi : 10.1126/science PMID 1172890

- Morrison KM, Miesegaes GR, Lumpkin EA, Maricich SM. (2009). Mammalian Merkel cells are descended from the epidermal lineage. Dev Biol. 2009 Sep 25. PMID 19782676

- Van Keymeulen A, Mascre G, Youseff KK, Harel I, Michaux C, De Geest N, Szpalski C, Achouri Y, Bloch W, Hassan BA, Blanpain C. (2009). Epidermal progenitors give rise to Merkel cells during embryonic development and adult homeostasis. J Cell Biol. 187(1):91-100. PMID 19786578

- Abesamis-Cubillan E, El-Shabrawi-Caelen L, LeBoit PE. Merked cells and sclerosing epithelial neoplasms. Am J Dermatopathol. 2000 Aug;22(4):311-5. PMID: 10949455

- M. Grandry: Recherches sur les corpuscles de Pasini. Journal de l’anatomie et de la physiologie normales et pathologiques de l’homme et des animaux, Paris, 1869, 6: 390-395.

- F. S. Merkel: Tastzellen und Tastkörperchen bei den Hausthieren und beim Menschen. Archiv für mikroskopische Anatomie, 1875, 11: 636-652.

- Zdenek Halata, Milos Grim, Klaus I. Baumann: Friedrich Sigmund Merkel and his "Merkel cell", morphology, development, and physiology: review and new results. The Anatomical Record. Part A, Discoveries in molecular, cellular, and evolutionary biology, Hoboken, NJ. March 2003, 271 (1): 225-239.