Hair follicles: anatomy, growth and what damage really means

Where is the follicle in relation to the visible hair?

A follicle extends down into the skin from its surface. During active production, the deepest part of a scalp follicle can reach the fatty tissue beneath the dermis. From outside, you mainly see the strand and the opening through which it emerges. That small opening does not reveal the whole organ or the condition of its deeper structures.

The hair shaft is the keratinised fibre; its cells have changed as they matured and no longer divide to make the strand longer. Growth is generated further down within the follicle. The strength of an existing length therefore depends on the condition of material already formed, while production of future hairs relies on cellular activity beneath the skin. Cutting the lengths or shaving the scalp therefore changes the accessible fibre without increasing the number of structures embedded in the skin.

Follicles occur across much of the body, with exceptions such as the palms and soles. They may produce barely noticeable vellus hairs or thicker, pigmented terminal hairs. An area with almost invisible hair is therefore not necessarily an area without follicles. Scalp hairs normally belong to the terminal category.

The appearance of your hair depends on both the fibres produced and their distribution. Many very fine hairs do not cover the skin in the same way as thicker strands. Separating the organ, the fibre and visible coverage helps explain why a loss of volume does not always mean that follicles have disappeared.

Bulb, papilla and matrix: which parts make a hair?

At the base of a growing follicle, the bulb is an enlarged region. It includes a matrix of cells that multiply and then differentiate, contributing to the hair and its inner supporting layers. Matrix cells are an actively producing population. Calling them simply “hair stem cells” overlooks the distinction between these cells and the reservoirs involved in their renewal.

The dermal papilla, next to the matrix, contains connective tissue cells. It contributes signals that organise growth. Blood supply allows living tissues to receive oxygen and nutrients, but the papilla is more than a supply point: communication with neighbouring cells is central to follicular function.

The epithelial cells producing the fibre and the connective tissue cells coordinating its development occupy different compartments. Their cooperation helps explain why isolating one cell population is insufficient to recreate a complete follicle.

Further up, a region called the bulge houses epithelial stem cells among other cell populations. It belongs to a more permanent part of the follicle. This location matters when considering injury: a temporary change in producing cells has different implications from destruction of the regions needed for renewal. The depth of an injury and the tissues affected therefore influence the potential for recovery.

Across the cycle, descendants of these stem cells help rebuild the compartments needed to produce another fibre. Kiani and colleagues describe this organisation by distinguishing reserve cells, proliferating cells and cells acquiring specialised functions.

Several sheaths surround the developing hair. The outer sheath forms part of the follicle’s epithelial structure, while the inner sheath accompanies the fibre during its formation. The shaft itself has an outer cuticle and a cortex, with a medulla sometimes present centrally. Confusing these layers with the bulb can lead to claims that a surface conditioner has an unproven effect on deeper tissues.

How are follicles connected to oil production and hair colour?

A sebaceous gland releases its contents into the upper follicular canal. Sebum contributes to the lubrication of the skin and hair. An oily scalp tells you something about secretion and accumulation at the surface. It does not, by itself, show that follicles are blocked or causing pattern baldness.

A small muscle, the arrector pili, is also attached to the follicular apparatus. Its contraction contributes to goosebumps. Nerve structures around this region help detect movement of the hair. A follicle therefore sits within living tissue, interacting with glands, nerves and surrounding cells.

Hair colour develops when melanocytes transfer pigment to the cells forming the growing fibre. Pigment cells and the cells building the hair have different functions. A white hair can continue to grow: reduced pigmentation is not the same as losing the organ that produces the strand. Plucking that hair does not restore its colouring mechanism.

Does a shed hair take its follicle with it?

A naturally released hair may have a pale, club-shaped end. This is a keratinised part of the strand, often described informally as a “white bulb”. It is not the entire productive bulb of a growing follicle, and it is certainly not the complete organ remaining within the skin.

This appearance develops during renewal. After active production, the lower follicle regresses; the strand stops lengthening and remains attached for a period before release. The persistent regions support another cycle. Our article on the hair growth cycle explains the stages and timings, which vary between individual hairs.

A pale end does not establish that every episode of shedding is normal, however. A sustained increase in hair loss or a visible reduction in coverage deserves assessment even when the collected strands look similar. Short fragments without an identifiable root end may instead reflect breakage. More than one mechanism can occur at the same time.

Deliberately pulling a hair out is a different event. It may remove a fibre with attached material without extracting the whole organ. Repeated trauma can nevertheless damage it. Avoid pulling hairs to test whether they are still viable: this cannot provide a reliable diagnosis and may add to the injury you are trying to understand.

What distinguishes a resting, miniaturised or destroyed follicle?

A resting follicle is passing through a physiological stage. Its retained strand has finished growing, but this does not mean that every cell in the organ is dead. During normal renewal, regression mainly affects lower compartments, while structures needed for the next cycle persist. Rest therefore does not describe irreversible destruction.

Miniaturisation is a gradual change in which the hairs produced become finer and their growth phase may shorten. It is a feature of androgenetic alopecia. A follicle may still make a fibre even though coverage is reduced. In susceptible men, the local response to androgens matters more than interpreting a hormone blood result in isolation.

Scarring destruction is a different process. Some inflammatory diseases permanently damage follicular structures, replacing them with scar tissue. Wolff and colleagues distinguish these conditions from non-scarring forms of hair loss. Treatment in this setting prioritises controlling disease activity and protecting areas that have not yet been destroyed.

Terms such as “dormant follicle” and “dead follicle” are not diagnoses you can establish in a mirror. Smooth-looking skin or increasingly fine strands cannot distinguish all these possibilities. Our article on scarring alopecia discusses these conditions in more detail. Recognising them requires examination and sometimes a biopsy.

What can spots or inflammation around hairs mean?

Folliculitis describes inflammation centred on hair follicles. Small red lesions, pustules or crusting may become noticeable, sometimes with tenderness. Their appearance cannot remotely identify an organism or establish that an antibiotic is appropriate. Other scalp disorders can also cause redness and itching.

The relationship with hair loss depends on the specific condition. Superficial inflammation and a disease capable of destroying follicles do not have the same course. Folliculitis decalvans, for example, is a scarring alopecia requiring dermatological care. Its name should not be applied to every spot appearing between hairs.

Recurrent lesions, pain, persistent crusting or an area losing coverage warrant an appointment with a GP or dermatologist. Squeezing spots or aggressively scrubbing the skin to “open the follicles” can add irritation. A clinician can examine the lesions, investigate their cause and decide whether a sample or another test is useful before treatment.

How does a clinician assess hair follicles?

Assessment starts with the history: the onset of shedding, changing hair thickness, patches or skin symptoms. Recent illness, medicines, styling habits and dietary restrictions provide different clues. An accurate list of products also helps identify possible irritation or treatment already attempted. No questionnaire alone measures the viability of every follicle.

Trichoscopy provides a magnified view of the scalp surface and hair fibres. A clinician looks for differences in diameter, broken hairs, follicular openings and changes around them. Singh and Muthuvel explain how these observations guide diagnosis. The device does not directly show the entire papilla or every stem cell deep within the skin.

Where the findings justify it, a small skin sample can be examined microscopically. This biopsy provides information about architecture and inflammation, particularly when scarring alopecia is suspected. Blood tests may answer a specific clinical question, such as possible iron deficiency or thyroid disease. They do not replace local examination and are not identical for everyone.

The assessment should clarify what has been identified and what remains uncertain. Ask whether the proposed goal concerns shedding, fibre thickness or inflammation. Improvement in one of these measures does not automatically mean an increase in follicle numbers. You can also tell your GP how the changes affect your wellbeing, as recommended by the NHS.

Which care measures protect hair and its attachment?

Conditioner can make detangling easier and reduce friction between strands. Adjusting heat styling or chemical processing can help limit fibre damage. These effects mainly concern the shaft, as discussed in Singh and Muthuvel’s diagnostic review. They can improve the condition of the lengths without demonstrating repair of destroyed follicular tissue.

Hairstyles that pull at the roots for long periods impose a different stress, transmitted to their attachment. Reducing that tension is sensible, especially when a style hurts. Broken hairs, thinning areas or skin lesions still require investigation of what is happening in the scalp. Changing a styling product cannot determine whether deeper damage is present.

A diet meeting ordinary nutritional needs supports tissue function. Suspected deficiency should be assessed and treated in its medical context; taking multiple supplements is not a regrowth test. Similarly, the word “natural” on an oil or serum establishes neither follicular benefit nor tolerability. Irritation is a reason to reconsider the routine rather than assume the product is working.

Medical treatment depends on the diagnosis, individual precautions and the agreed objective. A medicine studied for miniaturisation is not automatically appropriate for inflammatory hair loss or a painful scalp. Progress and adverse effects then need review, with a reassessment point discussed with the prescriber. The NHS recommends establishing the cause with a GP before considering a commercial hair clinic.

Can stem cells create new hair follicles?

Rebuilding a cycling part of an existing follicle differs from generating a new follicular organ. The first process is part of normal follicular biology. The second requires several cell populations, supporting layers and interactions to become organised within functional tissue. Advertising the presence of stem cells in a product does not establish that this organisation happens in a treated person.

In a study published in 2020, Lee and colleagues generated human skin organoids containing follicles from pluripotent stem cells. These structures were cultured in the laboratory and then grafted onto immunodeficient mice. This was experimental work involving human cells and an animal model, not a trial treating baldness in patients.

The authors described a level of maturity resembling foetal skin and highlighted the need for longer observation to establish follicle development and cycling. Their findings help explain how a follicle can be constructed biologically. They do not establish that an injection can rebuild a scarred area or provide an unlimited hair supply. Treatments marketed as regenerative need separate assessment of their own clinical evidence.

Follicle multiplication research is among the innovations being explored in hair restoration. When a treatment is offered, ask whether its reported results show thicker strands, improved hair density or demonstrated formation of new follicles. These outcomes answer different biological questions and do not support the same conclusions.

Does a transplant move strands or whole follicles?

Transplantation uses small pieces of tissue containing follicles, harvested from a donor region and implanted elsewhere. Scalp hairs can grow in follicular units, so an individual graft may contain several follicles. The stated graft count and the number of hairs those grafts carry are different quantities. Unit composition is one aspect of planning.

Comparing proposals by graft count alone can therefore be misleading if their composition or intended recipient area differs. Ask what was measured, how the available supply was estimated and what coverage the proposed procedure can reasonably aim to achieve.

The procedure redistributes an existing resource. It requires assessment of the donor region, the intended coverage and the condition responsible for the loss. An area without hair is not automatically suitable for surgery, particularly when inflammation remains active. Our guide to hair transplantation explains the decision process and the limits of surgery.

At Body Expert, planning a hair transplant in Istanbul therefore involves distinguishing preserved tissues, disease needing care and the coverage being sought. Our support includes 12-month post-operative follow-up carried out remotely. The medical team establishes suitability and individual expectations after assessment; understanding the anatomy helps you evaluate that proposal and discuss its limitations.

Sources

1. Kiani, M. T., Higgins, C. A., & Almquist, B. D. (2018). The hair follicle: An underutilized source of cells and materials for regenerative medicine. ACS Biomaterials Science & Engineering, 4(4), 1193–1207.
2. Singh, S., & Muthuvel, K. (2021). Practical approach to hair loss diagnosis. Indian Journal of Plastic Surgery, 54(4), 399–403.
3. Wolff, H., Fischer, T. W., & Blume-Peytavi, U. (2016). The diagnosis and treatment of hair and scalp diseases. Deutsches Ärzteblatt International, 113(21), 377–386.
4. Lee, J., Rabbani, C. C., Gao, H., Steinhart, M. R., Woodruff, B. M., Pflum, Z. E., Kim, A., Heller, S., Liu, Y., Shipchandler, T. Z., & Koehler, K. R. (2020). Hair-bearing human skin generated entirely from pluripotent stem cells. Nature, 582, 399–404.
5. National Health Service. (2024, January 24). Hair loss.
6. MedlinePlus. (2024, October 9). Folliculitis. A.D.A.M. Medical Encyclopedia.