Epidermis

Epidermis
Epidermis
	Microscopic image of the epidermis, which constitutes the outer layer of skin, shown here by the white bar
	Microscopic image showing the layers of the epidermis. The stratum corneum appears more compact in this image than above because of different sample preparation.
Details
Part of	Skin
System	Integumentary system
Identifiers
Latin	epidermis
MeSH	D004817
TA98	A16.0.00.009
TA2	7046
TH	H3.12.00.1.01001
FMA	70596
	Anatomical terms of microanatomy

The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis.^[1] The epidermis layer provides a barrier to infection from environmental pathogens^[2] and regulates the amount of water released from the body into the atmosphere through transepidermal water loss.^[3]

The epidermis is composed of multiple layers of flattened cells^[4] that overlie a base layer (stratum basale) composed of columnar cells arranged perpendicularly. The layers of cells develop from stem cells in the basal layer. The thickness of the epidermis varies from 31.2μm for the penis to 596.6μm for the sole of the foot with most being roughly 90μm. Thickness does not vary between the sexes but becomes thinner with age.^[5] The human epidermis is an example of epithelium, particularly a stratified squamous epithelium.

The word epidermis is derived through Latin from Ancient Greek epidermis, itself from Ancient Greek epi 'over, upon' and from Ancient Greek derma 'skin'. Something related to or part of the epidermis is termed epidermal.

^ Young B (2014). Wheater's functional histology a text and colour atlas. Elsevier. pp. 160 & 175. ISBN 9780702047473.
^ Marks JG, Miller J (2006). Lookingbill and Marks' Principles of Dermatology (4th ed.). Elsevier. pp. 1–7. ISBN 978-1-4160-3185-7.
^ Proksch E, Brandner JM, Jensen JM (December 2008). "The skin: an indispensable barrier". Experimental Dermatology. 17 (12): 1063–1072. doi:10.1111/j.1600-0625.2008.00786.x. PMID 19043850. S2CID 31353914.
^ McGrath JA, Eady RA, Pope FM (2004). Rook's Textbook of Dermatology (7th ed.). Blackwell Publishing. pp. 3.1–3.6. ISBN 978-0-632-06429-8.
^ Lintzeri, D.A.; Karimian, N.; Blume-Peytavi, U.; Kottner, J. (2022). "Epidermal thickness in healthy humans: a systematic review and meta-analysis". Journal of the European Academy of Dermatology and Venereology. 36 (8): 1191–1200. doi:10.1111/jdv.18123. ISSN 0926-9959. PMID 35366353.

[1] Young B (2014). Wheater's functional histology a text and colour atlas. Elsevier. pp. 160 & 175. ISBN 9780702047473.

[Lookingbill-2] Marks JG, Miller J (2006). Lookingbill and Marks' Principles of Dermatology (4th ed.). Elsevier. pp. 1–7. ISBN 978-1-4160-3185-7.

[Proksch-3] Proksch E, Brandner JM, Jensen JM (December 2008). "The skin: an indispensable barrier". Experimental Dermatology. 17 (12): 1063–1072. doi:10.1111/j.1600-0625.2008.00786.x. PMID 19043850. S2CID 31353914.

[Rooks-4] McGrath JA, Eady RA, Pope FM (2004). Rook's Textbook of Dermatology (7th ed.). Blackwell Publishing. pp. 3.1–3.6. ISBN 978-0-632-06429-8.

[Lintzeri_Karimian_Blume‐Peytavi_Kottner_2022_pp._1191–1200-5] Lintzeri, D.A.; Karimian, N.; Blume-Peytavi, U.; Kottner, J. (2022). "Epidermal thickness in healthy humans: a systematic review and meta-analysis". Journal of the European Academy of Dermatology and Venereology. 36 (8): 1191–1200. doi:10.1111/jdv.18123. ISSN 0926-9959. PMID 35366353.

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