Vernix caseosa, also known as vernix, is the waxy gray substance found that consumes 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]
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermal 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 nipples, areolar glands are specialized sebaceous glands for lubricating the nipples. Fordyce spots are benign, visible, sebaceous glands found usually on the lips, gums and inner cheeks, and genitals.
Fetal distress, also known as non-reassuring fetal status, is a condition during pregnancy or labor in which the fetus shows signs of inadequate oxygenation. Due to its imprecision, the term "fetal distress" has fallen out of use in American obstetrics. The term "non-reassuring fetal status" has largely replaced it. It is characterized by changes in fetal movement, growth, heart rate, and presence of meconium stained fluid.
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.
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 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.
Desquamation, or peeling skin, is the shedding of dead cells from the outermost layer of skin.
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.
In humans, the circulatory system is different before and after birth. The fetal circulation is composed of the placenta, umbilical blood vessels encapsulated by the umbilical cord, heart and systemic blood vessels. A major difference between the fetal circulation and postnatal circulation is that the lungs are not used during the fetal stage resulting in the presence of shunts to move oxygenated blood and nutrients from the placenta to the fetal tissue. At birth, the start of breathing and the severance of the umbilical cord prompt various changes that quickly transform fetal circulation into postnatal circulation.
Nutrition and pregnancy refers to the nutrient intake, and dietary planning that is undertaken before, during and after pregnancy. Nutrition of the fetus begins at conception. For this reason, the nutrition of the mother is important from before conception as well as throughout pregnancy and breastfeeding. An ever-increasing number of studies have shown that the nutrition of the mother will have an effect on the child, up to and including the risk for cancer, cardiovascular disease, hypertension and diabetes throughout life.
Intrauterine hypoxia occurs when the fetus is deprived of an adequate supply of oxygen. It may be due to a variety of reasons such as prolapse or occlusion of the umbilical cord, placental infarction, maternal diabetes and maternal smoking. Intrauterine growth restriction may cause or be the result of hypoxia. Intrauterine hypoxia can cause cellular damage that occurs within the central nervous system. This results in an increased mortality rate, including an increased risk of sudden infant death syndrome (SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy, attention deficit hyperactivity disorder, eating disorders and cerebral palsy.
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."
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
Epidermis-type lipoxygenase 3 is a member of the lipoxygenase family of enzymes; in humans, it is encoded by the ALOXE3 gene. This gene is located on chromosome 17 at position 13.1 where it forms a cluster with two other lipoxygenases, ALOX12B and ALOX15B. Among the human lipoxygenases, ALOXE3 is most closely related in amino acid sequence to ALOX12B. ALOXE3, ALOX12B, and ALOX15B are often classified as epidermal lipoxygenases, in distinction to the other three human lipoxygenases, because they were initially defined as being highly or even exclusively expressed and functioning in skin. The epidermis-type lipoxygenases are now regarded as a distinct subclass within the multigene family of mammalian lipoxygenases with mouse Aloxe3 being the ortholog to human ALOXE3, mouse Alox12b being the ortholog to human ALOX12B, and mouse Alox8 being the ortholog to human ALOX15B [supplied by OMIM]. ALOX12B and ALOXE3 in humans, Alox12b and Aloxe3 in mice, and comparable orthologs in other in other species are proposed to act sequentially in a multistep metabolic pathway that forms products that are structurally critical for creating and maintaining the skin's water barrier function.
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.
