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.
In Latin, vernix means varnish and caseosa means cheesy. The term was first published in 1846 in the Dunglison Dictionary of Medical Sciences. [1]
Vernix is produced during a distinct phase of the epidermal development. [2] 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. [1] [2] [3] Vernix, in itself, is also believed to aid in the formation of stratum corneum. [4] By early third trimester, the process is complete. [5]
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]
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. [6] Chemically, it is water (80%), lipids (10%) and proteins (10%). [1] The lipids include ceramides, cholesterol, fatty acids, triglycerides, waxes and sterol esters, squalene, and phospholipids; [1] multiple detailed analyses of the polar components have been done. [7] 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. [8]
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]
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]
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]
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]
Electrical isolation of the fetus is also thought to occur due to vernix caseosa (this could affect accurate fECG measurement of fetal heartbeat). [14]
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]
Granuloma and peritonitis of vernix have been observed in Caesarean sections. [2] High volumes of vernix cause Neonatal Aspiration Syndrome. [2]
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. [16]
Intrauterine growth restriction (IUGR), or fetal growth restriction, is the poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's birth weight percentile. The causes of IUGR are broad and may involve maternal, fetal, or placental complications.
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss.
A sebaceous gland or oil gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Surrounding the female nipple, areolar glands are specialized sebaceous glands for lubricating the nipple. Fordyce spots are benign, visible, sebaceous glands found usually on the lips, gums and inner cheeks, and genitals.
The umbilical artery is a paired artery that is found in the abdominal and pelvic regions. In the fetus, it extends into the umbilical cord.
The stratum corneum is the outermost layer of the epidermis. Consisting of dead tissue, it protects underlying tissue from infection, dehydration, chemicals and mechanical stress. It is composed of 15–20 layers of flattened cells with no nuclei and cell organelles.
Congenital syphilis is syphilis that occurs when a mother with untreated syphilis passes the infection to her baby during pregnancy or at birth. It may present in the fetus, infant, or later. Clinical features vary and differ between early onset, that is presentation before 2-years of age, and late onset, presentation after age 2-years. Infection in the unborn baby may present as poor growth, non-immune hydrops leading to premature birth or loss of the baby, or no signs. Affected newborns mostly initially have no clinical signs. They may be small and irritable. Characteristic features include a rash, fever, large liver and spleen, a runny and congested nose, and inflammation around bone or cartilage. There may be jaundice, large glands, pneumonia, meningitis, warty bumps on genitals, deafness or blindness. Untreated babies that survive the early phase may develop skeletal deformities including deformity of the nose, lower legs, forehead, collar bone, jaw, and cheek bone. There may be a perforated or high arched palate, and recurrent joint disease. Other late signs include linear perioral tears, intellectual disability, hydrocephalus, and juvenile general paresis. Seizures and cranial nerve palsies may first occur in both early and late phases. Eighth nerve palsy, interstitial keratitis and small notched teeth may appear individually or together; known as Hutchinson's triad.
At the end of pregnancy, the fetus must take the journey of childbirth to leave the reproductive mother. Upon its entry to the air-breathing world, the newborn must begin to adjust to life outside the uterus. This is true for all viviparous animals; this article discusses humans as the most-researched example.
Lanugo is very thin, soft, usually unpigmented, downy hair that is sometimes found on the body of a fetus or newborn. It is the first hair to be produced by the fetal hair follicles, and it usually appears around sixteen weeks of gestation and is abundant by week twenty. It is normally shed before birth, around seven or eight months of gestation, but is sometimes present at birth. It disappears on its own within a few weeks.
Fetal viability is the ability of a human fetus to survive outside the uterus. Viability depends upon factors such as birth weight, gestational age, and the availability of advanced medical care. In low-income countries, more than 90% of extremely preterm newborns die due to a lack of said medical care; in high-income countries, the vast majority of these newborns survive.
Desquamation occurs when the outermost layer of a tissue, such as the skin, is shed. The term is from Latin desquamare 'to scrape the scales off a fish'.
Large for gestational age (LGA) is a term used to describe infants that are born with an abnormally high weight, specifically in the 90th percentile or above, compared to other babies of the same developmental age. Macrosomia is a similar term that describes excessive birth weight, but refers to an absolute measurement, regardless of gestational age. Typically the threshold for diagnosing macrosomia is a body weight between 4,000 and 4,500 grams, or more, measured at birth, but there are difficulties reaching a universal agreement of this definition.
Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of 2,499 g or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal intensive care unit (NICU). They are also at increased risk for long-term health conditions which require follow-up over time.
Ceramides are a family of waxy lipid molecules. A ceramide is composed of sphingosine and a fatty acid joined by an amide bond. Ceramides are found in high concentrations within the cell membrane of eukaryotic cells, since they are component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer. Contrary to previous assumptions that ceramides and other sphingolipids found in cell membrane were purely supporting structural elements, ceramide can participate in a variety of cellular signaling: examples include regulating differentiation, proliferation, and programmed cell death (PCD) of cells.
Perinatal mortality (PNM) is the death of a fetus or neonate and is the basis to calculate the perinatal mortality rate. Perinatal means "relating to the period starting a few weeks before birth and including the birth and a few weeks after birth."
Urocanic acid is an intermediate in the catabolism of L-histidine. The cis-urocanic acid isomer is rare.
Corneocytes are terminally differentiated keratinocytes and compose most of the stratum corneum, the outermost layer of the epidermis. They are regularly replaced through desquamation and renewal from lower epidermal layers and are essential for its function as a skin barrier.
Arachidonate 12-lipoxygenase, 12R type, also known as ALOX12B, 12R-LOX, and arachidonate lipoxygenase 3, is a lipoxygenase-type enzyme composed of 701 amino acids and encoded by the ALOX12B gene. The gene is located on chromosome 17 at position 13.1 where it forms a cluster with two other lipoxygenases, ALOXE3 and ALOX15B. Among the human lipoxygenases, ALOX12B is most closely related in amino acid sequence to ALOXE3
CYP4F22 is a protein that in humans is encoded by the CYP4F22 gene.
Sucking blisters are a cutaneous condition on newborns that is present on their extremities at birth. This is not to be confused with sucking pads, which are similar in appearance. Sucking blisters are due to natural neonatal sucking reflexes on the affected areas in utero. These sucking blisters become present at birth when the sucking movements are very aggressive while in the uterus. These blisters are commonly found on the newborn's arms, fingers, or any body part they are able to suck on. It is a very rare condition, seen in less than 1% of newborns. It is difficult to diagnose because its appearance can be mistaken as other skin conditions. Diagnosis is usually done by eliminating other possible cutaneous conditions. This process of elimination includes examining blood culture, lesions, and inflammatory markers. This skin condition is usually self-inflicted, benign and can heal on its own. Sucking blisters do typically not require medical treatment and disappear within a week.
Branched-chain fatty acids (BCFA) are usually saturated fatty acids with one or more methyl branches on the carbon chain. BCFAs are most often found in bacteria, but can be found in nattō, dairy, vernix caseosa of human infants and California sea lions where they may play a role in fostering the development of their intestinal microbiota. Another waxy animal material containing BCFAs is lanolin.
