A hair follicle is a sac or cavity of the skin, in which the individual hair sits. Its growth on the scalp takes place in three phases, and lasts for about 3 – 4 years. This article provides some information on the growth cycle, drug testing, and infection of the same.
The term ‘follicle’ is derived from follis, which is a Latin word for bag. It is a complex structure responsible for the generation of hair fiber and hair growth. The sebaceous glands that secrete sebum open directly into the hair follicles. Hence, the number of these glands is directly proportional to 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 the definition, it is a sac-like structure located underneath the skin layer from which hair develops. Its anatomy and functions are very complex. its growth takes place 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 the studies conducted, the growth cycle of each follicle lasts for about 3 – 4 years. This length may differ according to difference in the location of hair. For instance, eyebrow hair takes about 1½-2 years to complete the cycle. At one time, approximately 85 – 90 percent of the total follicles remain in active growth state (anagen), and the length of scalp hair growth per year is about 10 – 15 cm. After the completion of telogen, it re-enters the anagen phase for growth. The gene regulation and chemical signals of these cycles have been studied in detail.
In a person with healthy hair, this growth cycle continues normally. Of course, this cavity-like structure shrinks under certain conditions, resulting in finer hair texture. Nevertheless, in people who are affected by baldness, the hair follicles at the bald spot stop growing as they should. The exact cause behind this abnormal growth cycle 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 the 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 research studies, traces of these substances remain in the follicles for a long period, even after they leave the bloodstream. One of the interesting facts about this drug testing is that the test report reveals the drug history of the candidate for the last 3 months or 90 days.
Medically referred to as folliculitis, an infected hair follicle resembles acne or pimple outbreak on the skin surface. The triggering factors for the damage 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 viruses.
In majority of the cases, these 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 such as pain, scarring, and hair loss. The practical solutions for mild infection are to identify the causes, avoid them, and follow proper personal hygiene tips. However, in the serious cases, the treatment that is recommended would include following tried-and-tested home remedies and the 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 the follicle. Similar to the epidermal cells that regulate shoot growth in plants, these stems cells are responsible for growth cycle of hair follicles. At present, research studies on tissue engineering of hair follicle are ongoing for generation of the 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 such related problems.
Disclaimer: This HealthHearty article is for informative purposes only, and should not be used as a replacement for expert medical advice.