# Cuticle

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Various biological tissues or structures

This article is about the general concept. For specific and related uses, see [Cuticle (disambiguation)](/source/Cuticle_(disambiguation)).

A **cuticle** ([/ˈkjuːtɪkəl/](https://en.wikipedia.org/wiki/Help:IPA/English)), or **cuticula**, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-[homologous](/source/Homology_(biology)), differing in their origin, structure, function, and chemical composition.

## Human anatomy

Anatomy of the basic parts of a human [nail](/source/Nail_(anatomy))

In [human anatomy](/source/Human_anatomy), "cuticle" can refer to several structures, but it is used in general parlance, and even by medical professionals, to refer to the thickened layer of skin surrounding fingernails and toenails (the [eponychium](/source/Eponychium)), and to refer to the superficial layer of overlapping cells covering the [hair](/source/Hair) shaft ([cuticula pili](/source/Cuticle_(hair))), consisting of dead cells, that locks the hair into its [follicle](/source/Hair_follicle).[1] It can also be used as a synonym for the [epidermis](/source/Epidermis_(skin)),[2] the outer layer of skin.

## Cuticle of invertebrates

See also: [Arthropod cuticle](/source/Arthropod_cuticle)

In [zoology](/source/Zoology), the [invertebrate](/source/Invertebrate) cuticle or cuticula is a multi-layered structure outside the [epidermis](/source/Epidermis_(skin)) of many invertebrates, notably [arthropods](/source/Arthropod) and [roundworms](/source/Nematode), in which it forms an [exoskeleton](/source/Exoskeleton) (see [arthropod exoskeleton](/source/Arthropod_exoskeleton)).

The main structural components of the nematode cuticle are [proteins](/source/Protein), highly cross-linked [collagens](/source/Collagen) and specialised insoluble proteins known as "cuticlins", together with [glycoproteins](/source/Glycoprotein) and [lipids](/source/Lipid).[3]

The main structural component of arthropod cuticle is [chitin](/source/Chitin), a [polysaccharide](/source/Polysaccharide) composed of [*N*-acetylglucosamine](/source/N-Acetylglucosamine) units, together with proteins and lipids. The proteins and chitin are cross-linked. The rigidity is a function of the types of proteins and the quantity of chitin. It is believed that the epidermal cells produce protein and also monitor the timing and amount of protein to be incorporated into the cuticle.[4]

Often, in the cuticle of [arthropods](/source/Arthropods), [structural coloration](/source/Structural_coloration) is observed, produced by nanostructures.[5] In the mealworm beetle, *[Tenebrio molitor](/source/Mealworm)*, cuticular color may suggest pathogen resistance in that darker individuals are more resistant to pathogens compared to more tan individuals.[6]

## Botany

Main article: [Plant cuticle](/source/Plant_cuticle)

[Epicuticular wax](/source/Epicuticular_wax) covering the [cuticle](/source/Plant_cuticle) of a leaf of *[Hosta](/source/Hosta) sieboldiana* makes it [hydrophobic](/source/Hydrophobic). Water, unable to [wet](/source/Wetting) the cuticle, beads up and runs off, carrying dust and soluble contamination with it. This self-cleaning property is variously called "ultrahydrophobicity" or "ultralyophobicity" in technical journals. More popularly it is known as the [*Lotus* effect.](/source/Lotus_effect)

In [botany](/source/Botany), [plant cuticles](/source/Plant_cuticle) are protective, hydrophobic, [waxy](/source/Wax) coverings produced by the epidermal cells of leaves, young shoots and all other aerial plant organs. Cuticles minimize water loss and effectively reduce pathogen entry due to their waxy secretion. The main structural components of [plant cuticles](/source/Plant_cuticle) are the unique [polymers](/source/Polymer) [cutin](/source/Cutin) or [cutan](/source/Cutan_(polymer)), impregnated with [wax](/source/Wax). Plant cuticles function as permeability barriers for water and water-soluble materials. They prevent plant surfaces from becoming [wet](/source/Wetting) and also help to prevent plants from drying out. [Xerophytic](/source/Xerophytic) plants such as [cacti](/source/Cacti) have very thick cuticles to help them survive in their arid climates. Plants that live in range of sea's spray also may have thicker cuticles that protect them from the toxic effects of [salt](/source/Salt).

Some plants, particularly those adapted to life in damp or aquatic environments, have an extreme resistance to wetting. A well-known example is the [sacred lotus](/source/Nelumbo_nucifera).[7] This adaptation is not purely the physical and chemical effect of a waxy coating but depends largely on the microscopic shape of the surface. When a hydrophobic surface is sculpted into [microscopic](/source/Microscopic_scale), regular, elevated areas, sometimes in [fractal](/source/Fractal) patterns, too high and too closely spaced for the surface tension of the liquid to permit any flow into the space between the plateaus, then the area of contact between liquid and solid surfaces may be reduced to a small fraction of what a smooth surface might permit.[8] The effect is to reduce wetting of the surface substantially.[9]

[Structural coloration](/source/Structural_coloration) is also observed in the cuticles of plants (see, as an example, the so-called "marble berry", *[Pollia condensata](/source/Pollia_condensata)*.[10]

## Mycology

Main article: [Pileipellis](/source/Pileipellis)

"Cuticle" is one term used for the outer layer of [tissue](/source/Tissue_(biology)) of a [mushroom](/source/Mushroom)'s [basidiocarp](/source/Basidiocarp), or "fruit body". The alternative term "[pileipellis](/source/Pileipellis)", Latin for "skin" of a "cap" (meaning "mushroom"[11]) might be technically preferable, but is perhaps too cumbersome for popular use. It is the part removed in "peeling" mushrooms. On the other hand, some [morphological](/source/Morphology_(biology)) terminology in mycology makes finer distinctions, such as described in the article on the "[pileipellis](/source/Pileipellis)". Be that as it may, the pileipellis (or "peel") is distinct from the [trama](/source/Trama_(mycology)), the inner fleshy tissue of a mushroom or similar fruiting body, and also from the [spore](/source/Spore)-bearing tissue layer, the [hymenium](/source/Hymenium).

## References

1. **[^](#cite_ref-1)** ["CUTICLE | meaning in the Cambridge English Dictionary"](https://dictionary.cambridge.org/dictionary/english/cuticle). Dictionary.cambridge.org. 2022-05-25. Retrieved 2022-05-31.

1. **[^](#cite_ref-2)** [*Cuticle*](https://web.archive.org/web/20190401181531/https://en.oxforddictionaries.com/definition/us/cuticle). Archived from [the original](https://en.oxforddictionaries.com/definition/us/cuticle) on 2019-04-01. Retrieved 2019-04-01.

1. **[^](#cite_ref-3)** Page, Anthony; Johnstone, I. L. (2007). ["The cuticle"](http://www.wormbook.org/chapters/www_cuticle/cuticle.pdf) (PDF). *WormBook*: 1–15. [doi](/source/Doi_(identifier)):[10.1895/wormbook.1.138.1](https://doi.org/10.1895%2Fwormbook.1.138.1). [PMC](/source/PMC_(identifier)) [4781593](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4781593). [PMID](/source/PMID_(identifier)) [18050497](https://pubmed.ncbi.nlm.nih.gov/18050497).

1. **[^](#cite_ref-4)** "insect physiology" The McGraw-Hill Encyclopedia of Science of Technology, Vol. 9, p. 233, 2007

1. **[^](#cite_ref-5)** Seago, Ainsley E.; Brady, Parrish; Vigneron, Jean-Pol; Schultz, Tom D. (28 October 2008). ["Gold Bugs and Beyond: A Review of Iridescence and Structural Colour Mechanisms in Beetles (Coleoptera)"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2586663). *Journal of the Royal Society Interface*. **6** (Suppl 2): S165–S184. [doi](/source/Doi_(identifier)):[10.1098/rsif.2008.0354.focus](https://doi.org/10.1098%2Frsif.2008.0354.focus). [PMC](/source/PMC_(identifier)) [2586663](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2586663). [PMID](/source/PMID_(identifier)) [18957361](https://pubmed.ncbi.nlm.nih.gov/18957361).

1. **[^](#cite_ref-6)** Armitage, S A O; Siva-Jothy, M T (2005-04-06). ["Immune function responds to selection for cuticular colour in Tenebrio molitor"](https://www.nature.com/articles/6800675). *Heredity*. **94** (6): 650–656. [Bibcode](/source/Bibcode_(identifier)):[2005Hered..94..650A](https://ui.adsabs.harvard.edu/abs/2005Hered..94..650A). [doi](/source/Doi_(identifier)):[10.1038/sj.hdy.6800675](https://doi.org/10.1038%2Fsj.hdy.6800675). [ISSN](/source/ISSN_(identifier)) [0018-067X](https://search.worldcat.org/issn/0018-067X). [PMID](/source/PMID_(identifier)) [15815710](https://pubmed.ncbi.nlm.nih.gov/15815710).

1. **[^](#cite_ref-7)** Quere, D.; Surface chemistry. Fakir droplets, Nature Materials 2002, 1, 14.

1. **[^](#cite_ref-8)** Onda, T.; Shibuichi, S.; Satoh, N.; Tsujii, K. (1996). "Super-Water-Repellent Fractal Surfaces". *Langmuir*. **12** (9): 2125–27. [doi](/source/Doi_(identifier)):[10.1021/la950418o](https://doi.org/10.1021%2Fla950418o).

1. **[^](#cite_ref-9)** Von Baeyer, H. C., "The lotus effect", *The Sciences*, 2000, January/February, 12

1. **[^](#cite_ref-10)** Vignolini, Silvia; Rudall, Paula J.; Rowland, Alice V.; Reed, Alison; Moyroud, Edwige; Faden, Robert B.; Baumberg, Jeremy J.; Glover, Beverley J.; Steiner, Ullrich (September 10, 2012). ["Pointillist Structural Color in Pollia Fruit"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3465391). *Proceedings of the National Academy of Sciences*. **109** (39): 15712–5. [Bibcode](/source/Bibcode_(identifier)):[2012PNAS..10915712V](https://ui.adsabs.harvard.edu/abs/2012PNAS..10915712V). [doi](/source/Doi_(identifier)):[10.1073/pnas.1210105109](https://doi.org/10.1073%2Fpnas.1210105109). [PMC](/source/PMC_(identifier)) [3465391](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3465391). [PMID](/source/PMID_(identifier)) [23019355](https://pubmed.ncbi.nlm.nih.gov/23019355).

1. **[^](#cite_ref-isbn0-398-06179-3_11-0)** [Jaeger, Edmund C.](/source/Edmund_Jaeger) (1959). [*A Source-Book of Biological Names and Terms*](https://archive.org/details/sourcebookofbiol0000jaeg). Illustrations: Merle Gish and the author (Third ed.). Springfield, IL: Charles C. Thomas, Publisher. p. [294](https://archive.org/details/sourcebookofbiol0000jaeg/page/294/mode/2up). [ISBN](/source/ISBN_(identifier)) [0398061793](https://en.wikipedia.org/wiki/Special:BookSources/0398061793). [OCLC](/source/OCLC_(identifier)) [16764689](https://search.worldcat.org/oclc/16764689). Retrieved 5 June 2023. {{[cite book](https://en.wikipedia.org/wiki/Template:Cite_book)}}: ISBN / Date incompatibility ([help](https://en.wikipedia.org/wiki/Help:CS1_errors#invalid_isbn_date))

## External links

- Media related to [кутикула](https://commons.wikimedia.org/wiki/%D0%BA%D1%83%D1%82%D0%B8%D0%BA%D1%83%D0%BB%D0%B0) at Wikimedia Commons

Authority control databases: National Japan

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Adapted from the Wikipedia article [Cuticle](https://en.wikipedia.org/wiki/Cuticle) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Cuticle?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.