Merkel nerve ending

Merkel nerve endings (also Merkel's disks,[1] or Merkel tactile endings[2]) are mechanoreceptors situated in the basal epidermis as well as around the apical ends or some hair follicles.[2] They are slowly adapting. They have small receptive fields measuring some millimeters in diameter. Most are associated with fast-conducting large myelinated axons.[1] A single afferent nerve fibre branches to innervate up to 90 such endings. Merkel nerve endings respond to light touch.[1] They respond to sustained pressure, and are sensitive to edges of objects. Their exact functions remain controversial.[2]

The Merkel nerve endings consist of a nerve ending associated with a flattened epithelial cell (Merkel cell); both the nerve ending and Merkel cell are independently mechanosensitive. The Merkel cell expresses the PIEZO2 mechanosensitive ion channels; mechanical activation of the channel causes depolarisation of the Merkel cell and consequent release of[1] serotonin into a synapse with the associated nerve ending, to also depolarise the later.[3] The nerve ending, meanwhile, expresses an unknown mechanosensitive channel.[1]

  1. ^ a b c d e Bear, Mark F.; Connors, Barry W.; Paradiso, Michael A. (2016). Neuroscience: Exploring the Brain (4th ed.). Philadelphia: Wolters Kluwer. pp. 417, 418, 420. ISBN 978-0-7817-7817-6.
  2. ^ a b c Standring, Susan (2020). Gray's Anatomy: The Anatomical Basis of Clinical Practice (42th ed.). New York: Elsevier. pp. 63–64. ISBN 978-0-7020-7707-4. OCLC 1201341621.
  3. ^ Chang, Weipang; Kanda, Hirosato; Ikeda, Ryo; Ling, Jennifer; DeBerry, Jennifer J.; Gu, Jianguo G. (13 September 2016). "Merkel disc is a serotonergic synapse in the epidermis for transmitting tactile signals in mammals". Proceedings of the National Academy of Sciences. 113 (37): E5491 – E5500. Bibcode:2016PNAS..113E5491C. doi:10.1073/pnas.1610176113. PMC 5027443. PMID 27573850.
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