Hair Follicles – Detailed Insight into the Structure and Growth Cycle

hair growth cycle

Since alopecia is such a common problem today, before you proceed to seek treatment a basic understanding of your hair follicles, primarily, its structure and growth cycle may interest you.

The hair follicle anatomy

A hair follicle looks like a stocking and is a vital organ of the mammalian skin. Found inside the dermal layer of our skin, it consists of 20 different types of cell. Hair growth depends on the function of the hair follicle. It regulates through a complex relationship between the immune cells, neuropeptides and the hormones. Such complex reaction results in the production of several types of hair found in different regions of the body.

The structure of a hair follicle might seem straightforward and simple, but the functions and the growth cycle are complex indeed. In case of the hampered normal cycle, problems like telogen effluvium or alopecia are likely to creep in.

The key components of a hair follicle
The four main components of hair follicle include:
Papilla: Found at the foot of the follicle, it consists of blood vessels and several connective tissues that accelerate hair growth.

Germinal Matrix: Often referred to as simply the matrix, it lies in the lower portion of the hair follicle. This is the region where the cells produce new hair when a strand of hair dies and falls off.

Bulb: The name itself clarifies its bulb-shaped structure that lies at the bottom portion of the follicle. It surrounds the matrix and the papilla and is nourished by the blood vessels. The bulb is the living part of the hair and the visible hair on the surface of the skin is dead. The different stem cells present in the bulb divide in every 72 hours. This growth is faster than any other cell of the human body. Hormones responsible for hair growth remain within the bulb.

Bulge: This portion lies in the middle portion of the hair follicle. Stem cells present inside the bulge are not only responsible for new hair follicle growth but also for maintaining the epidermis and the sebaceous glands. The arrector pilli finds its intersection point in the bulge. Arrector pilli is typical muscle tissue and it is the contraction of this muscle that causes ‘goosebumps.’

Four phases of the growth cycle

The rate of hair growth varies from one person to another. However, on an average, our hair grows near about half inch each month and about six inches each year. The hair growing process goes through four distinct phases:
Anagen or the Growth phase: This phase starts from the very first day of the birth of a hair strand. The anagen phase lasts for 2 to 7 years and is instrumental in determining the length of the hair.

Transition or the Catagen phase: In this transition phase, the growth of hair slows down for a few weeks and the hair follicles contract. This stage lasts for 10 days.

Telogen or the Resting phase: The resting phase of hair growth lasts for 3 months. When in this phase our hair stops growing and gets detached from the follicle. New hair enters the growth phase and pushes the old hair out causing hair fall. When in stress, more hair goes into the Telogen phase and results in rapid hair fall.

Exogen or the New Hair phase: Exogen stage is the continuation of the resting phase when new hair starts growing by shedding off the old hair. During this phase near about 50- 150 hairs fall off daily, which you can call as usual hair shedding.

Hair follicle: Function, Anatomy, and conditions

Once you know about the structure and growth cycle of hair follicle it is now time to understand its function, anatomy and different hair follicle problems.

Function
The main function of a hair follicle is to produce hair fibers regularly. However, this is not the only function that it performs. The hair follicles establish a close interaction with the neuroendocrine system of the skin. They also lend support to skin re-pigmentation and healing wounds. In some instances, they might also contribute to the formation of skin neoplasias.

Problematic conditions
Any issue in the hair follicle will give rise to numerous hair conditions. If you think that you are facing hair loss at an alarming rate, it is better to consult a dermatologist.
Some of the common hair follicle issues are:
Androgenetic alopecia: Also termed as male pattern baldness, it affects the growth cycle of the hair follicle badly. The hair cycle starts to slow down, gradually becomes weak, and finally stops.

Alopecia areata: Clubbed under the autoimmune diseases, the immune system often considers the hair follicles as foreign cells.

Folliculitis: When the hair follicles get inflamed, it results in conditions like Folliculitis. It looks like small red bumps on the skin and can be sore and itchy.

Telogen effluvium: This is a common but temporary form of hair loss, generally caused due to stress. Changing your life pattern might solve this issue.

Now that you have an overview of of your hair growth process and the reasons for hair loss, you are better informed. If you experience any of the above-mentioned problems, it is always wise to consult an expert hair transplant surgeon.