lanugo
{{short description|Type of soft baby hair}}
{{for|the insect genus|Lanugo (wasp){{!}}Lanugo (wasp)}}
{{Infobox medical condition (new)
| name = Lanugo
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| image = Lanugo.png
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| pronounce = {{IPAc-en|l|ə|ˈ|nj|uː|g|oʊ}}{{cite web|first=Dorland's Medical Dictionary for Health Consumers|last=Saunders, an imprint of Elsevier, Inc.|title=Lanugo : definition|url=http://medical-dictionary.thefreedictionary.com/lanugo|publisher=TheFreeDictionary|access-date=17 February 2013}}[http://dictionary.reference.com/browse/lanugo "lanugo"]. Random House Webster's Unabridged Dictionary.
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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.{{cite web|title=Definition of Lanugo|url=http://www.medterms.com/script/main/art.asp?articlekey=6210|publisher=MedicineNet: medterms medical dictionary|access-date=17 February 2013}}
It is replaced by hair covering the same surfaces, which is called vellus hair. This hair is thinner and more difficult to see. The more visible hair that persists into adulthood is called terminal hair. It forms in specific areas and is hormone-dependent.{{cite web|last1=Ascher-Walsh|first1=Charles J|title=What is lanugo?|url=http://www.pregnancyandbaby.com/baby/articles/942829/what-is-lanugo|website=Pregnancy&Baby|publisher=SheKnows|access-date=7 February 2013}} The term is from the Latin lana, meaning "wool."
Humans
=Fetal development=
During human development, the lanugo grows on fetuses as a normal part of gestation, but it is usually shed and replaced by vellus hair at about thirty-three to thirty-six weeks of gestational age. As the lanugo is shed from the skin, it is normal for the hair to be consumed by the developing fetus, since it drinks from the amniotic fluid and urinates into its environment. As a result, lanugo contributes to the newborn baby's meconium. The presence of lanugo on newborns is not necessarily a sign of premature birth, as it is also seen on infants born at thirty-nine weeks of gestation (full term).
Lanugo functions as an anchor to hold the vernix caseosa on the skin. Together they protect the delicate fetal skin from being damaged by the amniotic fluid.{{cite book|last=Moore|first=Keith L|title=The Developing Human: Clinically Oriented Embryology|date=Dec 19, 2011|publisher=Elsevier|isbn=978-1437720020|page=98|url=https://www.inkling.com/read/the-developing-human-moore-9th/chapter-19/development-of-skin-and}} The vernix caseosa also helps to prepare the fetus for life outside the womb. It provides lubrication for birth and contributes to thermoregulation, prevention of water loss, and innate immunity. Without the lanugo to anchor the vernix caseosa, these functions would be compromised.{{cite journal|last=Singh|first=G|author2=Archana |title=Unraveling the mystery of vernix caseosa|journal=Indian Journal of Dermatology|year=2008|volume=53|issue=2|pages=54–60|doi=10.4103/0019-5154.41645|pmid=19881987|pmc=2763724|doi-access=free}}
=Malnutrition=
In the absence of fat, lanugo grows to serve as a replacement insulator, and thus can be observed in malnourished patients, including those with eating disorders. When found along with other physical symptoms, for example, lanugo can help a physician make a diagnosis of anorexia nervosa or bulimia nervosa.{{cite journal |last1=Williams |first1=Pamela M. |last2=Goodie |first2=Jeffrey |last3=Motsinger |first3=Charles D. |title=Treating Eating Disorders in Primary Care |journal=American Family Physician |date=15 January 2008 |volume=77 |issue=2 |pages=187–195 |pmid=18246888 |url=http://www.aafp.org/afp/2008/0115/p187.html}}
=Teratoma=
It is often found in teratomas (congenital tumours).{{citation needed|date=December 2024}}
Other mammals
Lanugo is also common on other mammals. For example, seals{{cite journal|last=Androukaki|first=E.|author2=Fatsea, E., 't Hart, L., Osterhaus, A.D.M.E., Tounta, E. and Kotomatas, S.|title=Growth and Development of Mediterranean Monk Seal Pups during Rehabilitation|journal=Monachus Science Posters|date=May 2002|volume=5|issue=1|pages=This poster was presented at the 16th ECS (European Cetacean Society) Conference, "Marine Mammal Health: from Individuals to Populations", 7–11 April 2002, Liege, Belgium|url=http://www.monachus-guardian.org/mguard09/09scien3.htm|access-date=13 April 2013}} and elephants{{cite journal | url=https://www.jstor.org/stable/2559288 | jstor=2559288 | title=Ecology of the Asian Elephant in Lowland Dry Zone Habitats of the Mahaweli River Basin, Sri Lanka | last1=Ishwaran | first1=Natarajan | journal=Journal of Tropical Ecology | date=1993 | volume=9 | issue=2 | pages=169–182 | doi=10.1017/S0266467400007148 | s2cid=84830688 | url-access=subscription }}[http://elephant.elehost.com/About_Elephants/Anatomy/The_Hair/the_hair.html The Hair], Paul MacKenzie, [http://elephant.elehost.com/index.html Elephant Information Repository website][http://www.animalcorner.co.uk/wildlife/elephants/elephant_anatomy.html Elephant Hair], Elephant Anatomy, [http://www.animalcorner.co.uk/index.html Animal Corner website] {{webarchive|url=https://web.archive.org/web/20071117200853/http://www.animalcorner.co.uk/index.html |date=2007-11-17 }} are often born with a covering of lanugo. Some species of fetal whales and dolphins also have lanugo.{{cite book|last1=Coyne|first1=Jerry A.|title=Why Evolution is True|date=14 January 2010|publisher=OUP Oxford|isbn=9780191643842|page=89|url=https://books.google.com/books?id=J91Z6ED7MgEC&pg=PT89|language=en}}{{cite web|title=11 Cool Facts About Whales, Dolphins, and Porpoises|date=16 February 2021|website=NOAA Fisheries|url=https://www.fisheries.noaa.gov/feature-story/11-cool-facts-about-whales-dolphins-and-porpoises}}
References
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External links
{{sisterlinks|d=Q1540378|b=no|v=no|voy=no|m=no|mw=no|species=no|s=no|c=no|n=no|q=no}}
{{Medical resources
| DiseasesDB = 30821
| ICD10 = {{ICD10|Q|84|2|q|80}}
| ICD9 = {{ICD9|757.4}}
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{{Human hair}}
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