We all know that hair not only plays a vital role in the appearance of both men and women, but it also helps to transmit sensory information as well as create gender identification.
THE ORIGINS of HAIR
By week 22, a developing fetus has all of its hair follicles formed. At this stage of life there are about 5 million hair follicles on the body. There are a total of one million on the head, with one hundred thousand of those follicles residing on the scalp. This is the largest number of hair follicles a human will ever have, since we do not generate new hair follicles anytime during the course of our lives. Most people will notice that the density of scalp hair is reduced as they grow from childhood to adulthood. The reason: Our scalps expand as we grow.
THE TYPES of HAIR
The head contains two types of hair. One is called ‘Vellus’ which is fine and soft that is almost invisible. The other is called ‘Terminal’ and this is what you see on your head. It can grow long and is relatively coarse and more pigmented. Vellus hair can develop into terminal hair, as in the beards of adolescent males. On the other hand, terminal hair may become vellus, as happens during the development of common baldness, a process that is called ‘Miniaturization’.
THE FOLLICULAR UNIT
The hair of the scalp naturally grows in clusters of 1, 2, 3 and seldom, four hairs. These clusters we call ‘Follicular units’. This small group of hairs is separated from each other by hairless intervening skin.
THE HAIR FOLLICLE
Hair has two distinct structures – first, the follicle itself, which resides in the skin, and second, the shaft, which is what is visible above the scalp. The hair follicle is a tunnel-like segment of the epidermis that extends down into the dermis. The structure contains several layers that all have separate functions. At the base of the follicle is the Papilla, which contains capillaries, or tiny blood vessels that nourish the cells. The living part of the hair is the very bottom part surrounding the papilla, called the Bulb. The cells of the bulb divide every 23 to 72 hours, remarkably faster than any other cell in the body. Two sheaths, an inner and outer sheath, surround the follicle. These structures protect and form the growing hair shaft. The inner sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland, and sometimes an apocrine (sweat) gland. The outer sheath continues all the way up to the gland. A muscle called an erector pili muscle attaches below the gland to a fibrous layer around the outer sheath. When this muscle contracts, it causes the hair to stand up which also causes the sebaceous gland to secrete oil.
The sebaceous gland is vital because it produces sebum, which conditions the hair and skin. After puberty our body produces more sebum but as we age we begin to make less sebum. Women have far less sebum production than men do as they age.
THE HAIR SHAFT
The hair shaft is made of a hard protein called Keratin and is made in three layers. This protein is actually dead, so the hair that you see is not a living structure. The inner layer is the Medulla. The second layer is the Cortex and the outer layer is the Cuticle. The cortex makes up the majority of the hair shaft. The cuticle is a tightly formed structure made of shingle-like overlapping scales. It is both the cortex and the medulla that holds the hair’s pigment, giving it its color.
HAIR GROWTH CYCLES
Hair on the scalp grows about 0.3 to 0.4 mm/day or about 12 cm per year. Unlike other mammals, human hair growth and shedding is random and not seasonal or cyclical. At any given time, a random number of hairs will be in one of three stages of growth and shedding: Anagen, Catagen, and Telogen.
Anagen
Anagen is the active phase of the hair, and about 90% of all hairs are in this phase at any time The cells in the root of the hair are dividing rapidly. A new hair is formed and pushes the club hair (a hair that has stopped growing or is no longer in the anagen phase) up the follicle and eventually out. During this phase the hair grows about 1 cm every 28 days. Scalp hair stays in this active phase of growth for two to six years. Some people have difficulty growing their hair beyond a certain length because they have a short active phase of growth. On the other hand, people with very long hair have a long active phase of growth. The hair on the arms, legs, eyelashes, and eyebrows have a very short active growth phase of about 30 to 45 days, explaining why they are so much shorter than scalp hair.
Catagen
The catagen phase is a transitional stage. This phase lasts for about two to three weeks. Growth stops and the outer root sheath shrinks and attaches to the root of the hair. This is the formation of what is known as a club hair.
Telogen
Telogen is the resting phase and usually accounts for 10% of all hairs. This phase lasts for about 100 days for hairs on the scalp and longer for hairs on the eyebrow, eyelash, arm, and leg. During this phase, the hair follicle is completely at rest and the club hair is completely formed. Pulling out a hair in this phase will reveal a solid, hard, dry, white material at the root. About 100-150 telogen hairs are shed normally each day.
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Hair transplantation
The
hair transplant procedures
Hair transplantation has evolved a long, long way since it began in the early 1950’s. In 1939, a Japanese dermatologist, Dr. Okuda, published a revolutionary method in a Japanese medical journal of using small grafts that was similar to the way hair transplantation is performed today.
Follicular unit extraction or FUE is a hair transplant technique in which a small round punch (0.8 mm – 1.0 mm) is used to extract follicular units from a patient’s bald resistant donor areas. These follicular units are then transplanted into a patient’s balding areas.
The FUE brought us to the NO LOOK HAIR TRANSPLANT (NLHT). PROHAIR Clinic is the only clinic in the world who can perfrom this technique because we, the doctors at PROHAIR Hair Transplant Clinic devoloped it.
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