vernix caseosa

In Latin, vernix means varnish and caseosa means cheesy. The term was first published in 1846 in the Dunglison Dictionary of Medical Sciences.

Vernix is produced during a distinct phase of the epidermal development. Around the 21st week of gestation, periderm cells are being shed and replaced with stratum corneum; these shedding mix with secretions of sebum by the sebaceous glands to form vernix, which gradually covers the body in an anteroposterior and dorsoventral pattern.{{cite book | vauthors = Moore AL, Marshall CD, Nauta A, Lorenz HP, Longaker MT | chapter = Chapter 5 - Scarless Wound Healing: From Experimental Target to Clinical Reality|date=2019-01-01 | title = Principles of Regenerative Medicine | doi = 10.1016/B978-0-12-809880-6.00005-9 | edition = Third |pages=65–92| veditors = Atala A, Lanza R, Mikos AG, Nerem R |place=Boston|publisher=Academic Press|language=en|isbn=978-0-12-809880-6 | s2cid = 81194374}} Vernix, in itself, is also believed to aid in the formation of stratum corneum.{{cite book | vauthors = Hoath SB, Shah KN | chapter = 49 - Physiologic Development of the Skin|date=2017-01-01| doi = 10.1016/B978-0-323-35214-7.00049-4 | title =Fetal and Neonatal Physiology | edition = Fifth |pages=498–514.e4| veditors = Polin RA, Abman SH, Rowitch DH, Benitz WE |publisher=Elsevier |language=en |isbn=978-0-323-35214-7 }} By early third trimester, the process is complete.{{cite book | vauthors = Karperien M, Roelen BA, Poelmann RE, Gittenberger-de Groot AC, Hierck BP, DeRuiter MC, Meijer D, Gibbs S | chapter = Chapter 3 - Tissue Formation during Embryogenesis|date=2015-01-01| doi = 10.1016/B978-0-12-420145-3.00003-1 | title = Tissue Engineering | edition = Second |pages=67–109 | veditors = Blitterswijk CA, De Boer J |place=Oxford |publisher=Academic Press |isbn=978-0-12-420145-3 | url = https://ris.utwente.nl/ws/files/31463929/Karperien2014tissue.pdf}}

Soon enough, part of the vernix is emulsified by increasing concentrations of pulmonary surfactants and desiccates, only to be consumed by the fetus; a corresponding increase in amniotic fluid turbidity is noticed.

Vernix has a highly variable makeup but is primarily composed of sebum, cells that have sloughed off the fetus's skin and shed lanugo hair.{{cite book | vauthors = Schachner LA, Hansen RC |title=Pediatric dermatology |publisher=Mosby |location=St. Louis |year=2003 |isbn=978-0-323-02611-6 |pages=206–7}} Chemically, it is water (80%), lipids (10%) and proteins (10%). The lipids include ceramides, cholesterol, fatty acids, triglycerides, waxes and sterol esters, squalene, and phospholipids; multiple detailed analyses of the polar components have been done.{{cite journal | vauthors = Harazim E, Vrkoslav V, Buděšínský M, Harazim P, Svoboda M, Plavka R, Bosáková Z, Cvačka J | display-authors = 6 | title = O-acylceramides in vernix caseosa | journal = Journal of Lipid Research | volume = 59 | issue = 11 | pages = 2164–2173 | date = November 2018 | pmid = 30254076 | doi = 10.1194/jlr.M088864 | pmc = 6210899 | url = http://www.jlr.org/content/59/11/2164 | doi-access = free }} The total fatty acid profile in vernix (either as part of lipids or as fatty acids) contains a variety of less common fatty acids, such as omega-7 polyunsaturated fatty acids or non-methylene-interrupted omega-3 fatty acids.{{Cite journal |last1=Menzel |first1=Jan Philipp |last2=Young |first2=Reuben S. E. |last3=Benfield |first3=Aurélie H. |last4=Scott |first4=Julia S. |last5=Wongsomboon |first5=Puttandon |last6=Cudlman |first6=Lukáš |last7=Cvačka |first7=Josef |last8=Butler |first8=Lisa M. |last9=Henriques |first9=Sónia T. |last10=Poad |first10=Berwyck L. J. |last11=Blanksby |first11=Stephen J. |date=2023-07-04 |title=Ozone-enabled fatty acid discovery reveals unexpected diversity in the human lipidome |journal=Nature Communications |language=en |volume=14 |issue=1 |pages=3940 |doi=10.1038/s41467-023-39617-9 |pmid=37402773 |pmc=10319862 |bibcode=2023NatCo..14.3940M |issn=2041-1723|doi-access=free }}

The protein composition is relatively understudied. Vernix of term infants has more squalene and a higher wax ester to sterol ester ratio than preterm infants.

Vernix is composed of mobile corneocytes embedded in an amorphous lipid matrix. Precise biological mechanisms leading to its formation are poorly understood.{{cite book | vauthors = Hoath SB, Narendran V, Visscher MO |first3=Marty O.| chapter =Vernix Caseosa and Innate Immunity|date=2011|title =Innate Immune System of Skin and Oral Mucosa|pages=145–169|publisher=John Wiley & Sons, Ltd|language=en|doi=10.1002/9781118025338.ch8|isbn=978-1-118-02533-8 }}

The cells are polygonal or ovoid in shape, malleable, and lack nuclei; typical thickness is 1-2 μm. Nuclear ghosts are frequently observed and Acid Phosphatase Activity is nonuniform. Keratin filaments build a scaffold like structure which form a water-storage area. As opposed to stratum corneum, the vernix corneocytes lack desmosomal attachment and the lipid layer is more disordered.{{cite journal | vauthors = Rissmann R, Groenink HW, Weerheim AM, Hoath SB, Ponec M, Bouwstra JA | title = New insights into ultrastructure, lipid composition and organization of vernix caseosa | journal = The Journal of Investigative Dermatology | volume = 126 | issue = 8 | pages = 1823–33 | date = August 2006 | pmid = 16628195 | doi = 10.1038/sj.jid.5700305 | doi-access = free }}

Vernix is a white viscous cream-like substance in appearance.

The water is not uniformly distributed throughout, but rather exclusively present in the sponge-like corneocytes; despite its high water content, vernix is non-polar (due to lipids) and more vapor-permeable than stratum corneum.{{cite book|last=Hoath|first=Steven|url=https://archive.org/details/neonatalskin00hoat|title=Neonatal skin : structure and function|publisher=Dekker|year=2003|isbn=0-8247-0887-3|edition=2. ed., rev. and expanded.|location=New York [u.a.]|pages=[https://archive.org/details/neonatalskin00hoat/page/n205 193]–208|url-access=limited}}{{cite journal | vauthors = Visscher M, Narendran V | title = The Ontogeny of Skin | journal = Advances in Wound Care | volume = 3 | issue = 4 | pages = 291–303 | date = April 2014 | pmid = 24761361 | pmc = 3985523 | doi = 10.1089/wound.2013.0467 | url = }}

Vernix appears in all full term infants but with widely varying body-coverage, while premature and post-mature births generally do not display any.{{Citation|last=Sidbury|first=Robert|title=Newborn Skin Development|date=2018|url=https://www.sciencedirect.com/science/article/pii/B9780323401395001030|work=Avery's Diseases of the Newborn|pages=1468–1474.e1|publisher=Elsevier|language=en|doi=10.1016/B978-0-323-40139-5.00103-0|isbn=978-0-323-40139-5|access-date=2021-01-04}}

It is theorized (and observed) to serve several purposes:{{cite journal | vauthors = Singh G, Archana G | title = Unraveling the mystery of vernix caseosa | journal = Indian Journal of Dermatology | volume = 53 | issue = 2 | pages = 54–60 | date = 2008 | pmid = 19881987 | pmc = 2763724 | doi = 10.4103/0019-5154.41645 | doi-access = free }}

• Waterproofing the skin, whilst in gestation.
• Lubricating the infant's skin, and facilitating easy passage through the birth canal.
• Preventing infections — primarily as a mechanical barrier and secondarily via the presence of lysozyme, lactoferrin and antimicrobial components in peptide layer.
• Moisturizing the stratum corneum whilst in gestation (and controlled drying in post-partum phase).
• Thermoregulation in post-partum phase — evidence is mixed.
• Quick healing of epidermal wounds.
• Development of gut, after intra-uterine consumption.

Electrical isolation of the fetus is also thought to occur due to vernix caseosa (this could affect accurate fECG measurement of fetal heartbeat).{{cite journal | vauthors = Chiera M, Cerritelli F, Casini A, Barsotti N, Boschiero D, Cavigioli F, Corti CG, Manzotti A | display-authors = 6 | title = Heart Rate Variability in the Perinatal Period: A Critical and Conceptual Review | language = English | journal = Frontiers in Neuroscience | volume = 14 | pages = 561186 | date = 2020 | pmid = 33071738 | doi = 10.3389/fnins.2020.561186 | pmc = 7544983 | doi-access = free }}

Vernix is used as a reliable site-of-record for measuring cocaine exposure in pregnant women.{{Cite journal |last1=Moore |first1=C. |last2=Dempsey |first2=D. |last3=Deitermann |first3=D. |last4=Lewis |first4=D. |last5=Leikin |first5=J. |date=October 1996 |title=Fetal cocaine exposure: analysis of vernix caseosa |journal=Journal of Analytical Toxicology |volume=20 |issue=6 |pages=509–511 |doi=10.1093/jat/20.6.509 |issn=0146-4760 |pmid=8889690|doi-access=free }} Using vernix for diagnosing uterine rupture and amniotic fluid embolism has been proposed.

Granuloma and peritonitis of vernix have been observed in Caesarean sections. High volumes of vernix cause Neonatal Aspiration Syndrome.

Vernix is thought to be unique to human fetal development; in 2018, vernix-like material was reportedly obtained from pups of the California sea lion.{{cite journal | vauthors = Wang DH, Ran-Ressler R, St Leger J, Nilson E, Palmer L, Collins R, Brenna JT | title = Sea Lions Develop Human-like Vernix Caseosa Delivering Branched Fats and Squalene to the GI Tract | journal = Scientific Reports | volume = 8 | issue = 1 | pages = 7478 | date = May 2018 | pmid = 29748625 | pmc = 5945841 | doi = 10.1038/s41598-018-25871-1 | bibcode = 2018NatSR...8.7478W }}

Vernix feet.jpg|Vernix on a newborn's legs and feet.

Newborn minutes after delivery.jpg|Traces of vernix on a full term newborn.

Postpartum baby3.jpg|Closeup of baby's face right after birth, skin covered in vernix and some blood.

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Category:Immune system

Category:Neonatology

Category:Skin