Hair Follicle
The term follicle is derived from follis, a Latin word meaning bag. It is a complex structure responsible for hair fiber generation and hair growth. The sebaceous glands that secrete sebum open directly into the hair follicles. Hence, the number of these glands is directly proportional the density of hair. Associated with sweat glands, papilla, root sheath, matrix, bulge, hair fiber and nerve system, this structure plays a crucial role in the health of hair strands.
What is a Hair Follicle?
According to hair follicle definition, it is a saclike structure located underneath the skin layer from which hair develops. The anatomy and functions of hair follicle are very complex. Nevertheless, one thing is for sure, and that is the growth of hair follicle in a highly coordinated cycle. There are three primary phases in the growth cycle, which occur successively. The first is anagen (an active growth phase), followed by catagen (a transitional and regressing phase) and the last is telogen (a resting or quiescent phase).
As per studies conducted on scalp hair follicles, the growth cycle of each follicle lasts for about 3-4 years. This length may differ according to difference in the location of hair. Say for example, eyebrow hair takes about 1-2 years to complete the cycle. At one time, approximately 85-90 percent of the total hair follicles remain in active growth state (anagen). And the length of scalp hair growth per year is about 10-15 cm. After completion of telogen, the hair follicle reenters anagen phase for growth. The gene regulation and chemical signals of these cycles have been studied in detail.
In a person with healthy hair, the hair follicle growth cycle continues normally. Of course, this cavity like structure shrinks under certain conditions, resulting in finer hair texture. Nevertheless, in people who have existing baldness problems, the small hair follicles at the bald spot stop growing as they should. The exact causes behind this abnormal hair follicle growth cycling is not clear. However, it is strongly believed that genetic factors and hormones are the root causes for baldness.
What is a Hair Follicle Drug Test?
In addition to other drug testing samples, like urine and oral secretion, the hair also serves as a reliable biological specimen. In the procedure for a hair follicle drug test, a sample of hair follicle is collected from the candidate to examine the presence of drugs and recreational substances. During the circulation of nutrients and oxygen, small amounts of processed drugs from the blood are deposited in the follicles. As per researches, traces of these substances remain in the hair follicles for long-term period, even after they leave the bloodstream.One of the interesting facts about hair follicle drug testing is that the test report reveals the drug history of the candidate for the last 3 months or 90 days.
Hair Follicle Infection
Nearly of us come across hair follicle infection in scalp or other part of the body. Medically referred to as folliculitis, an infected hair follicle resembles acne or pimple outbreak in the skin surface. The triggering factors of damaged hair follicles are shaving, excessive sweating, wearing tight clothes, wounds and dermatitis amongst others. Some notable symptoms of folliculitis are itchiness, eruption of red bumps and fluid filled blisters. In some cases, they become a site for infection by bacteria, fungi and virus.
In majority of the cases, hair follicle infections are temporary and resolve on their own with time. However, recurrent folliculitis and severe infections in some areas require prompt treatment to avoid outcomes like, pain, scarring and hair loss. The practical solutions for mild infection are to identify the causes, avoid them and follow proper personal hygiene tips. In case of serious cases, recommended infected hair follicle treatment includes following home remedies and application of topical antibiotics for effective results.
In a nutshell, the science behind the constant growth of hair is the presence of stem cells at the base of hair follicle. Just like the epidermal cells that regulates shoot growth in plants, these stems cells are responsible for growth cycle of hair follicles. At present, researches on tissue engineering of hair follicle is ongoing for generation of hair follicles in large amounts using a single follicle. If this turns out to be a feasible option, it could be used as a potential treatment for hair loss, baldness and other hair follicle related problems.
