Hair growth begins in follicles, which are living sacs of skin tissue in the surface of your scalp out of which hair starts to grow in groupings of 1 to 4 hairs. For 2-8 years at a time, your follicles are working continuously, growing hair, and pushing it up and through your scalp at a growth rate of about a half-inch per month. Eventually, each follicle enters a resting stage and its hair stops growing. Finally, the hair is shed from the follicle, allowing a new one to spring up in its place and start the cycle all over again.
The portion of the hair that we can see is called the shaft. Each shaft of hair protrudes from its follicle, which is a tube-like pouch just below the surface of the skin. The hair is attached to the base of the follicle by the papilla, or hair root, which is where the hair actually grows and is nourished by blood capillaries. As it grows, sebaceous, or oil, glands lubricate and add shine to your hair.
Like the rest of the body, hair is made of cells. New cells form at the root, and the hair is gradually pushed further and further out of the follicle. Cells at the base of each hair are close to the blood capillaries, and are still living. As they get pushed further away from the base of the follicle, they no longer have any nourishment. As a result they die, and are transformed into a hard protein called keratin, the same material that makes up your fingernails and toenails.
In short, each hair we see above the skin is basically dead protein. It is the follicle, which lies in the skin, that is the essential living and growing part of your hair.
Normal hair follows a continuously repeating cycle of growth, shedding, resting, and regrowth. Since all of these are happening at the same time, three strands of hair in the same area of your head might each be in a different growth phase. Each phase has specific characteristics that determine the length of the hair:
At any given time, 85% to 90% of your hair is in the first of these phases, actively growing. The remaining 10% to 15% is transitioning or resting in the other two phases. If a follicle is destroyed for any reason, no new hair will grow from it. A normal, healthy head of hair has approximately 100,000 hairs growing.
Thinning hair is most commonly caused when hair follicles are constricted by dihydrotestosterone (DHT), a chemical buildup which can lead to male pattern baldness. FDA-cleared "LaserComb" technology and the FDA-approved medication Minoxidil (a regrowth agent included in Hair Club's EXT® system) can halt or reverse hair thinning by clearing DHT out of your system, leaving your hair free to grow thicker and more naturally again.
Hair transplant surgery works by placing healthy follicles that are more resistant to DHT from the back and sides of the head back into the system of blood vessels and capillaries that nourish your hair, when placed in areas of thinning or balding where they take root and re-start the cycle beginning with the telogen phase.