Hair follicle
In addition to the term hair follicle, hair follicle is a common name. This term describes all anatomical structures that are involved in the anchoring of the hair in the skin surrounding the place where the hair is formed.
Anatomy and function
In simplified terms, one can imagine the hair follicle as a thread-like indentation in the skin, which is surrounded by special concentric layers of cells. From the outside in, these layers comprise an outer epithelial hair root sheath, also called the stratum basale, a unicellular layer of cells, the so-called "companion layer", and an inner epithelial hair root sheath, which in turn can be divided into three further layers. These are called Henle's layer, Huxley's layer and cuticle, coming from the outside in. The base of the hair follicle is formed by the hair bulb, also called the hair bulb, while the roof of the hair follicle is called the hair funnel or infundibulum.
The entire hair follicle is surrounded by a layer of connective tissue, which embeds it in the surrounding tissue and makes it movable in relation to it. The outer epithelial hair follicle consists of several layers of cells that are very rich in glycogen and provide important nutrients for hair growth. These cells are not horny in the area of the entire hair follicle. At the seamless transition to the epidermis, the epidermis, the cells of this layer are now keratinized. The uncornified "companion layer" is connected to the already horny Henle layer via numerous desmosomes, adhesive contacts between the cells.
The "companion layer" slides together with the entire inner epithelial hair root sheath on the outer epithelial hair root sheath towards the surface, where they are abraded and the hair is exposed. This complex of layers serves as an anchor for the hair in the skin, since the side of the cuticle facing the hair has barb-like structures on its surface. The hair bulb is slightly widened like a piston and contains the so-called matrix cells and melanocytes. Matrix cells are very divisive cells that are not horny at first and later make up the main part of the hair when they become horny. Melanocytes are cells that produce pigment and largely define hair color. This pigment is released to the matrix cells, which means that it reaches the tip as the hair grows.
The hair funnel represents the opening of the hair follicle for the hair. This way it reaches the surface and can grow unhindered. A sebum gland and a sweat gland open into the hair funnel. Shortly below the sebum gland, a small muscle inserts into the connective tissue root sheath, which can turn the hair of the body into goose bumps.
Abscess on the hair follicle
An abscess that affects the entire follicle is called a boil. If several boils come together, this is called carbuncle. This abscess can form on any hairy part of the body. However, they are particularly common on the neck, nose, chest, armpit, groin, buttocks and inner thighs. Such an accumulation has also been described for the external auditory canal. A boil is characterized by a central plug of pus surrounded by a concentric reddened area that reacts painfully to pressure. A carbuncle has a larger area of pus and is characterized by greater pain.
The cause of an abscess on the hair follicle is usually an infection with Staphylococcus aureus, a bacterium, or a mixed infection of several types of bacteria. In addition to bacteria, there are also common causes. Often too tight or chafing clothing is to blame, as is poor hygiene after a shave. Since a boil or carbuncle is potentially life-threatening, medical advice should be sought if a boil is suspected, provided that the abscess cannot be emptied without assistance. In any case, there is a risk of sepsis, which is why the doctor removes the pus and, if necessary, treats it with antibiotics. Carbuncles are particularly dangerous in the oral cavity, as the germs quickly reach the brain via the bloodstream or lymph. For people who are prone to abscesses, particular emphasis can be placed on hygiene and loose-fitting clothing. This significantly reduces a new occurrence.
Read more on the topic: Boils and carbuncles
Inflammation of the hair follicle
Inflammation of the hair follicle is called folliculitis. This is noticeable as redness and slight pain in one or more hairs. In contrast to an abscess of the hair follicle, an inflammation of the hair follicle only affects the upper parts (infundibulum). If this is blocked by horn material, which causes the inflammation to spread to the entire hair follicle, it is called a boil, i.e. an abscess of the hair follicle. Risk factors for inflammation of the hair follicles are diseases such as diabetes mellitus and acne, but also therapy with cortisone ointments or thick hair. This is especially true of men with heavy beards. Such inflammation is also more common in immunocompromised patients.
Read more on the topic: Hair follicle inflammation
As with an abscess, the cause of the inflammation can be bacterial. Viruses and fungi are also possible causes. As a rule, inflammation of the hair follicle is not a problem. Although the redness in the hair area is often perceived as unaesthetic, it should subside within a few days. In a few cases, inflammation turns into a boil. The danger here lies in the development of life-threatening sepsis. Therefore, if in doubt, you should seek medical treatment if a painful plug of pus develops.
Recurring inflammation of a hair follicle can lead to scarring. In severe cases, the cause of the inflammation is treated, i.e. an ointment is applied locally against the inflammation, the bacteria or fungi. Systemic therapy can also be used if it is suspected of having spread to the body. Recently, phototherapy has also been offered as an alternative. The affected area is irradiated with UV light for about 15 minutes.Treatment with chamomile has proven to be a home remedy for mild inflammation.
Find out more about the topic: Folliculitis
