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Vellus hair is short, thin, light-colored, and barely noticeable
hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Phy ...

hair
that develops on most of a person's body during
childhood Biologically, a child (plural children) is a human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, hairlessness, and intelligence allowing the use of cult ...

childhood
. Exceptions include the
lip Lips are a visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be an ...

lip
s, the back of the
ear The ear is the organ of hearing and, in mammals, balance. In mammals, the ear is usually described as having three parts—the outer ear The outer ear, external ear, or auris externa is the external part of the ear, which consists ...

ear
, the palm of the
hand A hand is a prehensile, multi- fingered appendage located at the end of the forearm The forearm is the region of the upper limb between the Elbow-joint, elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, ...

hand
, the sole of the foot, some external
genital A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction Sexual reproduction is a type of reproduction that involves a complex Biological life cycle, life cycle in which a gamete (such as a sp ...

genital
areas, the
navel The navel (clinically known as the umbilicus, commonly known as the belly button) is a protruding, flat, or hollowed area on the abdomen The abdomen (colloquially called the belly, tummy, midriff or stomach) is the part of the body between th ...

navel
, and
scar A scar is an area of fibrosis, fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other Organ (anatomy), organs, and biological tissue, tissues of the b ...
tissue. The density of hair – the number of
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given orga ...

hair follicle
s per
area Area is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value in ...

area
of skin – varies from person to person. Each strand of vellus hair is usually less than 2 mm (1/13 inch) long and the
follicle
follicle
is not connected to a
sebaceous gland A sebaceous gland is a microscopic exocrine Exocrine glands are gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormone A hormone (from the Greek participle , "setting in motion") is a ...
. Vellus hair is most easily observed on children and adult women, who generally have less
terminal hair In humans, terminal hair is thick and long, such as what grows on the scalp, as compared with vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles foun ...
to obscure it. Vellus hair is not
lanugo Lanugo is very thin, soft, usually unpigmented, downy hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemi ...

lanugo
hair. Lanugo hair is a much thicker type of hair that normally grows only on
fetuses A fetus American and British English spelling differences#ae and oe, or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of developme ...

fetuses
. Vellus hair is differentiated from the more visible terminal or
androgenic hair Body hair, or androgenic hair, is the terminal hair In humans, terminal hair is thick and long, such as what grows on the scalp, as compared with vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is ...
, which develops only during and after
puberty Puberty is the process of physical changes through which a child Biologically, a child (plural children) is a human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natur ...

puberty
, usually to a greater extent on men than it does on women. The
Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an appa ...
uses the word ''vellus'' to designate "a fleece" or "wool." Vellus hair is sometimes colloquially referred to as peach fuzz, due to its resemblance to the
downy Downy, also known as Lenor in Europe, Russia and Japan, is a brand of fabric softener A fabric softener (or conditioner) is a conditioner (chemistry), conditioner that is typically applied to laundry during the rinse cycle in a washing machine to r ...
epidermic growths on the
peach The peach (''Prunus persica'') is a deciduous In the fields of horticulture Horticulture is the art of cultivating plants in gardens to produce food and medicinal ingredients, or for comfort and ornamental purposes. Horticulturists grow ...

peach
fruit.


Development

Vellus hair replaces
lanugo hair Lanugo is very thin, soft, usually unpigmented, downy hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin ...
on a human fetus at 36 to 40 weeks of
gestationGestation is the period of development during the carrying of an embryo An embryo is the early stage of development of a multicellular organism. In general, in organism In biology, an organism (from Ancient Greek, Greek: ὀργανι ...
. The growth cycle of vellus hair is different from the growth cycle of
terminal hair In humans, terminal hair is thick and long, such as what grows on the scalp, as compared with vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles foun ...
. At
puberty Puberty is the process of physical changes through which a child Biologically, a child (plural children) is a human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natur ...

puberty
,
androgen An androgen (from Greek ''andr-'', the stem of the word meaning "man") is any natural or synthetic steroid hormone A steroid hormone is a steroid that acts as a hormone. Steroid hormones can be grouped into two classes: corticosteroids (typic ...
hormones cause much of the vellus hair to turn into
terminal hair In humans, terminal hair is thick and long, such as what grows on the scalp, as compared with vellus hair Vellus hair is short, thin, light-colored, and barely noticeable hair Hair is a protein filament that grows from follicles foun ...
and stimulate the growth of new hair in the armpit and the
pubic area
pubic area
. In men, this change in vellus hair usually occurs on the face and the body.


Function

Vellus hair provides both thermal insulation and cooling for the body. This insulation regulates body temperature: the vellus hair functions like a
wick
wick
for sweat. While a skin pore is open, sweat wets a strand of vellus hair. The sweat on the external part of the strand evaporates. More sweat wets the external part of the vellus strand and then evaporates. This process is called
perspiration Perspiration, also known as sweating, is the production of fluids secreted by the sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, fl ...
.


Clinical significance


Overgrowth

The unusual growth of vellus hair can be a side effect of some types of disease. An abundance of vellus hair can develop from an increase in the production of the
cortisol Cortisol is a steroid hormone A steroid hormone is a steroid , hypothetical a steroid with 32 carbon atoms. Its core ring system (ABCD), composed of 17 carbon atoms, is shown with IUPAC The International Union of Pure and Applied C ...

cortisol
hormone in a person with
Cushing's syndrome Cushing's syndrome is a collection of signs and symptoms due to prolonged exposure to glucocorticoids such as cortisol. Signs and symptoms may include hypertension, high blood pressure, abdominal obesity but with thin arms and legs, reddish str ...

Cushing's syndrome
.
Anorexia nervosa Anorexia nervosa, often referred to simply as anorexia, is an eating disorder An eating disorder is a mental disorder defined by abnormal eating behaviors that negatively affect a person's health, physical or mental health, mental health. On ...
increases vellus hair. Vellus hair can also be found in men with
male pattern baldness Pattern hair loss is hair loss Hair loss, also known as alopecia or baldness, refers to a loss of hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. ...

male pattern baldness
or with
hirsutism Hirsutism is excessive body hair Body hair, or androgenic hair, is the terminal hair that develops on the human body The human body is the structure of a human being. It is composed of many different types of cells that together create t ...
. Hormonal fluctuations in pregnant women cause foetal vellus hair to change to terminal hair. The terminal hair is usually shed after the birth of the baby upon the return of the hormones to the normal levels. *
Trichostasis spinulosa Trichostasis spinulosa is a common but rarely diagnosed disorder of the hair follicles that clinically gives the impression of blackheads, but the follicles are filled with funnel-shaped, horny plugs that are bundles of vellus hair Vellus hair is ...
– A tuft of vellus hair located in a keratinous sheath is diagnostic. * Frontal fibrosing alopecia, a clinical variant of lichen planopilaris, is a female scarring alopecia characterized by progressive recession of the frontotemporal hairline. It is characterised by the absence of vellus hair in the hairline. * Eruptive vellus hair cyst (EVHC), a benign dermatologic condition in children and young adults.


Undergrowth

The following conditions may affect growth of the vellus hairs: * Perioral dermatitis – the hairs may be completely absent in affected
facial A facial is a family of skin care treatments for the face The face is the front of an animal's head that features the eyes Eyes are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on ma ...

facial
areas.


References

{{Human hair Hair anatomy