Hair follicle

A Hair follicle is a part of the skin that grows hair by packing old cells together. Attached inside the top of the follicle are sebaceous glands, which are tiny sebum-producing glands in the skin.

Structure

The hair follicle is a dynamic organ found in mammalian skin. It resides in the dermal layer of the skin and is made up of 20 different cell types, each with distinct functions. The hair follicle regulates hair growth via a complex interaction between hormones, neuropeptides, and immune cells. This interaction induces the hair follicle to produce different types of hair as seen on different parts of the body.

Function

The primary function of a hair follicle is to produce a hair. Hair follicles cover the entire body, with the exception of the palms of the hands and soles of the feet. Hair follicles also have other functions. They are responsible for the production of sebum, which is an oily substance that helps to keep the skin and hair moisturized.

Hair Growth Cycle

The hair growth cycle consists of three stages: anagen, catagen, and telogen. Anagen is the growth phase; catagen is the degenerating phase; and telogen, the resting or quiescent phase.

Disorders

There are many disorders that involve the hair follicle. Some of these include alopecia, hirsutism, hypertrichosis, and folliculitis.

See Also

• Hair
• Skin
• Sebaceous gland
• Alopecia
• Hirsutism
• Hypertrichosis
• Folliculitis

References

• 
  Hair follicle diagram
• Arm hair
  Arm hair
• Hair follicle anatomy
  Hair follicle anatomy
• 
  Hair follicle cycling video
• Hair follicle video
  Hair follicle video
• 
  Alopecia
• Alopecia scales
  Alopecia scales
• Lupus erythematosus
  Lupus erythematosus
• 
  Hidradenitis