Acuticle(/ˈkjuːtɪkəl/), orcuticula,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,differing in their origin, structure, function, and chemical composition.
Human anatomy
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Inhuman 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 (theeponychium), and to refer to the superficial layer of overlapping cells covering thehairshaft (cuticula pili), consisting of dead cells, that locks the hair into itsfollicle.[1]It can also be used as a synonym for theepidermis,[2]the outer layer of skin.
Cuticle of invertebrates
editInzoology,theinvertebratecuticle or cuticula is a multi-layered structure outside theepidermisof many invertebrates, notablyarthropodsandroundworms,in which it forms anexoskeleton(seearthropod exoskeleton).
The main structural components of the nematode cuticle areproteins,highly cross-linkedcollagensand specialised insoluble proteins known as "cuticlins", together withglycoproteinsandlipids.[3]
The main structural component of arthropod cuticle ischitin,apolysaccharidecomposed ofN-acetylglucosamineunits, 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 monitors the timing and amount of protein to be incorporated into the cuticle.[4]
Often, in the cuticle ofarthropods,structural colorationis observed, produced by nanostructures.[5]In the mealworm beetle,Tenebrio molitor,cuticular color may suggest pathogen resistance in that darker individuals are more resistant to pathogens compared to more tan individuals.[6]
Botany
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Inbotany,plant cuticlesare protective, hydrophobic,waxycoverings 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 ofplant cuticlesare the uniquepolymerscutinorcutan,impregnated withwax.Plant cuticles function as permeability barriers for water and water-soluble materials. They prevent plant surfaces from becomingwetand also help to prevent plants from drying out.Xerophyticplants such ascactihave 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 ofsalt.
Some plants, particularly those adapted to life in damp or aquatic environments, have an extreme resistance to wetting. A well-known example is thesacred lotus.[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 intomicroscopic,regular, elevated areas, sometimes infractalpatterns, 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 colorationis also observed in the cuticles of plants (see, as an example, the so-called "marble berry",Pollia condensata.[10]
Mycology
edit"Cuticle" is one term used for the outer layer oftissueof amushroom'sbasidiocarp,or "fruit body". The alternative term "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, somemorphologicalterminology in mycology makes finer distinctions, such as described in the article on the "pileipellis".Be that as it may, the pileipellis (or" peel ") is distinct from thetrama,the inner fleshy tissue of a mushroom or similar fruiting body, and also from thespore-bearing tissue layer, thehymenium.
References
edit- ^"CUTICLE | meaning in the Cambridge English Dictionary".Dictionary.cambridge.org. 2022-05-25.Retrieved2022-05-31.
- ^Cuticle.Archived fromthe originalon 2019-04-01.Retrieved2019-04-01.
- ^Page, Anthony; Johnstone, I. L. (2007)."The cuticle"(PDF).WormBook:1–15.doi:10.1895/wormbook.1.138.1.PMC4781593.PMID18050497.
- ^"insect physiology" The McGraw-Hill Encyclopedia of Science of Technology, Vol. 9, p. 233, 2007
- ^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)".Journal of the Royal Society Interface.6(Suppl 2): S165–S184.doi:10.1098/rsif.2008.0354.focus.PMC2586663.PMID18957361.
- ^Armitage, S A O; Siva-Jothy, M T (2005-04-06)."Immune function responds to selection for cuticular colour in Tenebrio molitor".Heredity.94(6): 650–656.doi:10.1038/sj.hdy.6800675.ISSN0018-067X.PMID15815710.
- ^Quere, D.; Surface chemistry. Fakir droplets, Nature Materials 2002, 1, 14.
- ^Onda, T.; Shibuichi, S.; Satoh, N.; Tsujii, K. (1996). "Super-Water-Repellent Fractal Surfaces".Langmuir.12(9): 2125–27.doi:10.1021/la950418o.
- ^Von Baeyer, H. C., "The lotus effect",The Sciences,2000, January/February, 12
- ^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".Proceedings of the National Academy of Sciences.109(39): 15712–5.Bibcode:2012PNAS..10915712V.doi:10.1073/pnas.1210105109.PMC3465391.PMID23019355.
- ^Jaeger, Edmund C.(1959).A Source-Book of Biological Names and Terms.Illustrations: Merle Gish and the author (Third ed.). Springfield, IL: Charles C. Thomas, Publisher. p.294.ISBN0398061793.OCLC16764689.Retrieved5 June2023.
External links
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