What is Vellus Hair?
Vellus hair references short and fine hairs on the body or scalp that are commonly referred to as “peach fuzz” or baby hair. In fact, this type of hair is more observable on women and children than men. This is because vellus hairs are translucent and easily concealed by the thicker terminal hairs. Babies especially have an abundance of this type of hair. During puberty, many vellus hairs transform into stronger and move easily seen terminal hairs. The origins of the word “vellus” roughly translates into “fleece” or “wool”.
What is the purpose of Vellus Hair?
The purpose of this hair type does not seem any different than other hairs found throughout the body. As with other hairs, this particular type serves as insulation from cold weather, and as a way to perceive physical touch. These hairs also allows sweat to bead and evaporate more efficiently, which is what cools off the body.
What is the Structure of Vellus Hair?
These hairs are much shorter than normal, and their follicles do not have sebaceous glands. The hair shaft is quite narrow, sometimes more than the root sheath itself. The hair bulb is located higher than most hair follicles, and follicle itself is not very deep. Since this type of hair does not have a sebaceous gland, and terminal hairs do not come in until puberty, some hair specialists theorize that sebaceous glands are what causes the onset of acne during puberty.
Where can Vellus Hair Be Found?
These types of hairs can be found throughout the body. They can be located on the face (even on women), on the fingers, the chest, the back, and even on the tops of the toes. Vellus hairs cannot be found behind the ears (though they can be found on the earlobe itself), on the forehead, on the eyelids, on the nose, on the lips, on scars, or on the palms. The amount of these hairs is genetic, meaning that some people have a genetic proclivity to have more vellus hair than others, and to retain a higher amount of these hairs throughout life.
Vellus Hair Abnormalities
The following diseases are known to cause the following symptoms relating to vellus hairs:
- Cushing’s disease – The adrenal gland secretes an abnormal amount of hormones in the bloodstream, which creates an imbalance that causes an extreme amount of these small hairs to form.
- Male Pattern Hair Loss (MPH) – In certain cases of MPH, an abundance of these hairs form.
- Hirsutism – This is seemingly the exact opposite of MPH because it is characterized by an amount of hair growth on the body and face. As such, a vast number of vellus hairs are known to occur throughout the duration this condition as well.
- Anorexia Nervosa – A dietary condition that can prevent vellus hairs from receiving enough nutrition to transform into terminal hairs.
- A rare birth defect can sometimes cause babies to be born with vellus hairs that mature into terminal hairs. This is caused by a hormonal imbalance that triggers the hairs to mature well before puberty.