Lanugo (/la·nu·go/, from Latin lana "wool") is very fine, soft, and usually unpigmented, downy hair as can be found on the body of a fetus or newborn baby. It is the first hair to be produced by the fetal hair follicles, and it usually appears on the fetus at about 5 months of gestation. It is normally shed before birth, around 7 or 8 months of gestation but is sometimes present at birth and disappears on its own within a few days or weeks.
Lanugo hair will invariably be shed by three to four months after birth. It is replaced by hair covering the same surfaces called vellus hair, but this hair is finer and more difficult to see. The more visible hair that continues into adulthood is called terminal hair. This forms in specific areas and is hormone dependant.
During human development, the lanugo grows on fetuses as a normal part of gestation, but is usually shed and replaced by vellus hair at about 33 to 36 weeks of gestational age. As the lanugo is shed from the skin, it is normal for the developing fetus to consume the hair with the fluid, since it drinks from the amniotic fluid and urinates it back into its environment. Subsequently, the lanugo contributes to the newborn baby's meconium. The presence of lanugo in newborns is a sign of premature birth.
It has been hypothesised that the lanugo of human fetuses aids in temperature regulation.
Lanugo 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.
It is often found in teratomas (congenital tumours).
In non-human animals
Fetal whales, like humans and all other primates, also have lanugo.
- "Lanugo : definition". TheFreeDictionary. Retrieved 17 February 2013.
- "Definition of Lanugo". MedicineNet: medterms medical dictionary. Retrieved 17 February 2013.
- "What is lanugo?". SheKnows. Retrieved 17 February 2013.
- "You and your baby at 21-24 weeks". NHS choices. NHS. Retrieved 29 November 2011.
- "Treating Eating Disorders in Primary Care", P.M. Williams, et al, American Family Physician, Vol 77 (2): January 15, 2008
- Androukaki, E.; Fatsea, E., 't Hart, L., Osterhaus, A.D.M.E., Tounta, E. and Kotomatas, S. (May 2002). "Growth and Development of Mediterranean Monk Seal Pups during Rehabilitation". Monachus Science Posters 5 (1): 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. Retrieved 13 April 2013.
- Ecology of the Asian Elephant in Lowland Dry Zone Habitats of the Mahaweli River Basin, Sri Lanka Natarajan Ishwaran Journal of Tropical Ecology, Vol. 9, No. 2 (May, 1993), pp. 169-182
- The Hair, Paul MacKenzie, Elephant Information Repository website
- Elephant Hair, Elephant Anatomy, Animal Corner website
|Look up lanugo in Wiktionary, the free dictionary.|