Vernix caseosa

Newborn baby with vernix on parts of her skin

Vernix caseosa, also known as vernix, is the waxy or cheese-like white substance found coating the skin of newborn human babies.

Etymology

In Latin, vernix means varnish and caseosa means cheesy.

Characteristics

Composition

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.[1] 12% of the dry weight of vernix is composed of branched chain fatty acids,[2] cholesterol and ceramide. Vernix of term infants has more squalene and a higher wax ester to sterol ester ratio than preterm infants.[1]

Comparison of lipid components of vernix caseosa, stratum corneum and skin surface (sebaceous):[3][4]

Amino acid composition of vernix caseosa:[4][5]

Morphology

Cells of vernix are typically polygonal or ovoid in shape and lack nuclei. Nuclear ghosts are frequently observed. Vernix corneocytes lack desmosomal attachment and this distinguishes them from corneocytes found in mature stratum corneum.[6] Thickness of a corneocyte is 1-2 µm. These cells are surrounded by a layer of amorphous lipids lacking typical lamellar architecture present in mature stratum corneum.[4]

Physical properties

Vernix is not uniformly distributed, but rather present in form of cellular sponges. The critical surface tension of vernix is 39 dyne/cm.[7] Despite its water content (82%), vernix is nonpolar. These features point towards the "waterproofing" function of vernix, thereby preventing heat loss soon after birth.[4]

Biological properties

Vernix provides electrical isolation for the fetus,[8] which is presumably an important aspect of developing fetal anatomy.[4] Early scientific studies indicated increased evaporative heat loss in infants when vernix was removed soon after birth;[9] but newer reports confirm that washing skin surface after birth reduces evaporative water losses compared to surface of newborns in which vernix is left in situ.[10] Vernix is hydrophobic. Vernix is believed to assist in the development of the human intestinal microbiota.[2]

Secretion

The sebum in vernix is produced in utero by the sebaceous glands around the 20th week of gestation. Vernix appears primarily in full term infants, while premature and postmature births generally lack any.[1] Postdates desquamation (flakey skin in babies born >42 weeks) is thought to be due to loss of vernix.

Functions

Vernix is theorized to serve several purposes, including moisturizing the infant's skin, and facilitating passage through the birth canal. It serves to conserve heat and protect the delicate newborn skin from environmental stress. Vernix is also thought to have an antibacterial effect;[4] though there is little evidence to support a chemical role of vernix in protecting the infant from infection, it may form a physical barrier to the passage of bacteria.[1]

Non-human observations

Vernix has also been been observed in aquatic mammals such as seals. Don Bowen, a marine biologist from Nova Scotia observes that seals have vernix with harbour seals who swim immediately having more than other seals which do not swim for at least 10 days.[11]

Additional images

References

  1. 1 2 3 4 Schachner, Lawrence A.; Hansen, Ronald C. (2003). Pediatric dermatology. St. Louis: Mosby. pp. 206–7. ISBN 978-0-323-02611-6.
  2. 1 2 Ran-Ressler RR, Devapatla S, Lawrence P, Brenna JT (2008). "Branched chain fatty acids are constituents of the normal healthy newborn gastrointestinal tract" (PDF). Pediatric Research. 64 (6): 605–609. doi:10.1203/PDR.0b013e318184d2e6. PMC 2662770Freely accessible. PMID 18614964.
  3. ↑ Sumida Y, Yakumaru M, Tokitsu Y, et al. Studies on the function of Vernix caseosa: The secrecy of Baby's skin. Cannes, France: International Federation of the Societies of Cosmetic Chemists 20th International Conference; 1998. pp. 1–7.
  4. 1 2 3 4 5 6 Hoath, Steven (2003). Neonatal skin : structure and function (2. ed., rev. and expanded. ed.). New York [u.a.]: Dekker. pp. 193–208. ISBN 0-8247-0887-3.
  5. ↑ Baker, SM; Balo, NN; Abdel Aziz, FT (Mar–Apr 1995). "Is vernix caseosa a protective material to the newborn? A biochemical approach.". Indian Journal of Pediatrics. 62 (2): 237–9. doi:10.1007/bf02752334. PMID 10829874.
  6. ↑ Pickens, WL; Warner, RR; Boissy, YL; Boissy, RE; Hoath, SB (Nov 2000). "Characterization of vernix caseosa: water content, morphology, and elemental analysis.". The Journal of Investigative Dermatology. 115 (5): 875–81. doi:10.1046/j.1523-1747.2000.00134.x. PMID 11069626.
  7. ↑ Youssef, W; Wickett, RR; Hoath, SB (Feb 2001). "Surface free energy characterization of vernix caseosa. Potential role in waterproofing the newborn infant.". Skin Research and Technology. 7 (1): 10–7. doi:10.1034/j.1600-0846.2001.007001010.x. PMID 11301635.
  8. ↑ Wakai, RT; Lengle, JM; Leuthold, AC (Jul 2000). "Transmission of electric and magnetic foetal cardiac signals in a case of ectopia cordis: the dominant role of the vernix. caseosa.". Physics in Medicine and Biology. 45 (7): 1989–95. doi:10.1088/0031-9155/45/7/320. PMID 10943933.
  9. ↑ Saunders, Colman (1 August 1948). "The vernix caseosa and subnormal temperature in premature infants.". The Journal of Obstetrics and Gynaecology of the British Empire. 55 (4): 442–444. doi:10.1111/j.1471-0528.1948.tb07409.x. PMID 18878967.
  10. ↑ Riesenfeld B, Stromberg B, Sedin G. The influence of vernix caseosa on water transport through semipermeable membranes and the skin of full-term infants. Neonatal Physiological Measurements: Proceedings of the Second International Conference on Fetal and Neonatal Physiological Measurements, 1984:3–6.
  11. ↑ Vaneechoutte, Mario; Kuliukas, Algis; Verhaegen, Marc. Was Man more Aquatic in the Past?. Bentham E Books. p. 157. Retrieved Sep 18, 2016.

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