Vernix caseosa
Vernix caseosa, also known as vernix, is the waxy white substance found coating the skin of newborn human babies.[1] It is produced by dedicated cells and is thought to have some protective roles during fetal development and for a few hours after birth.
Etymology
In Latin, vernix means varnish and caseosa means cheesy. The term was first published in 1846 in the Dunglison Dictionary of Medical Sciences.[1]
In-utero development
Vernix is produced during a distinct phase of the
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.[2]
Characteristics
Composition
Vernix has a highly variable makeup but is primarily composed of
The protein composition is relatively understudied.[1] Vernix of term infants has more squalene and a higher wax ester to sterol ester ratio than preterm infants.[6]
Morphology
Vernix is composed of mobile corneocytes embedded in an amorphous lipid matrix.[1] Precise biological mechanisms leading to its formation are poorly understood.[9]
The cells are polygonal or ovoid in shape, malleable, and lack nuclei; typical thickness is 1-2 µm.[1] Nuclear ghosts are frequently observed and Acid Phosphatase Activity is nonuniform.[1] Keratin filaments build a scaffold like structure which form a water-storage area.[1] As opposed to stratum corneum, the vernix corneocytes lack desmosomal attachment and the lipid layer is more disordered.[10]
Physical properties
Vernix is a white viscous cream-like substance in appearance.[1]
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.[1][11][12]
Functions
Vernix appears in all full term infants but with widely varying body-coverage, while premature and post-mature births generally do not display any.[6][2][13]
It is theorized (and observed) to serve several purposes:[1][2][11]
- 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).[14]
Medical uses
Vernix is used as a reliable site-of-record for measuring cocaine exposure in pregnant women.[2][15] Using vernix for diagnosing uterine rupture and amniotic fluid embolism has been proposed.[2]
Disorders
Granuloma and peritonitis of vernix have been observed in Caesarean sections.[2] High volumes of vernix cause Neonatal Aspiration Syndrome.[2]
Other species
Vernix is thought to be unique to human fetal development; in 2018, vernix-like material was reportedly obtained from pups of the
Additional images
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Vernix on a newborn's legs and feet.
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Traces of vernix caseosa on a full term newborn.
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Closeup of baby's face right after birth, skin covered in vernix and some blood.
References
- ^ PMID 31507021.
- ^ PMID 19881987.
- S2CID 81194374.
- ISBN 978-0-323-35214-7.
- ISBN 978-0-12-420145-3.
- ^ ISBN 978-0-323-02611-6.
- PMID 30254076.
- PMID 37402773.
- ISBN 978-1-118-02533-8.
- PMID 16628195.
- ^ ISBN 0-8247-0887-3.
- PMID 24761361.
- ISBN 978-0-323-40139-5, retrieved 2021-01-04
- PMID 33071738.
- PMID 8889690.
- PMID 29748625.