How hair grows has a lot more in common with your garden than just terminology. Read on to find out more…
In the beginning...
Hair growth begins deep inside the hair follicle. Yet the live part of the hair is at the very bottom of the follicle: the bulb.
The bulb, or hair root, contains living cells that grow the hair while the visible part of the hair, the shaft, is already dead.
The other important part of the hair is the bulge. This is where stem cells are stored to regenerate the bulb when the hair falls out near the end of each growth cycle. It is the bulge which needs to be targeted by any successful form of permanent hair removal as, once the stem cells are removed, no hair can ever grow again!.All images on this page can be enlarged. Click on or touch the image.
Hair ColoursAll natural hair colours are the result of just 2 types of hair pigments and both of these are derivatives of melanin.
Eumelanin is the dominant pigment in brown and black hair, while pheomelanin is dominant in red hair. Blond hair is actually the result of having little pigmentation at all in the hair strand while grey and white hair occur when melanin production stops.
Hair thickness is simply determined by follicle size, not colour or curliness. Anyone's hair volume can therefore be thin, normal, or thick from the same number of hairs of any colour.
Curly HairThe shape of the hair shaft has a direct effect on the curliness of your hair. A very round shaft resists movement with the same pressure in every direction encouraging it to remain straight.
The flatter or more elliptical the hair shaft becomes the curlier hair gets. Because the shape favours bending in one direction, the hair soon begins to curl after leaving the follicle.
Hair TypesHair grows everywhere on the body except on mucus membranes and glabrous skin such as the palms of the hands, soles of the feet, and lips. As a new-born, we have all our hair follicles, but just one hair type grows in them: vellus hair.
Vellus hair is a fine, slow growing and almost transparent hair often simply called peach fuzz. The thicker, pigmented, faster-growing hair is called terminal hair. Over time, growth and sex hormones influence how hair grows. They cause hair follicles to switch production from vellus to terminal hair in the typical male and female hair growth patterns.
Hair Growth CycleHair follows a growth cycle with three distinct phases: anagen, catagen, and telogen. All 3 occur simultaneously across the skin with each hair on the body at its own phase of development. While one hair may be in the anagen phase, another may be in the telogen phase.
The overall effect is for the volume of hair to appear constant despite some follicles being dormant (no hair) and others just beginning to grow new hair. The average rate of growth for hair is 1.25cm per month or 15cm per year.
Hair length owes more to the length of the anagen (growing) phase than by the speed of hair growth. Scalp hair has the longest growth stage and is therefore capable of growing the longest hair while eyelashes and eyebrows have the fastest growth rate yet remain much shorter because of their brief growing phase.
Hair Growth Stages
Anagen PhaseThe anagen phase is known as the growth phase. This is the phase where the hair grows approximately 1cm per month. Hair on the scalp can grow for 2 – 6 years in anagen phase. At the other extreme, eyebrows will grow for just 4 – 8 weeks. The longer the hair stays in the anagen phase, the longer it will grow.
Catagen PhaseThe catagen phase is known as the transitional phase. During this time, which lasts about 2 weeks, the bulb detaches and "rests". The hair remains in the follicle but is cut off from its blood supply and stops growing.
Telogen PhaseDuring the telogen, or resting phase, the follicle remains dormant for 1 – 4 months. Around 10% - 15% of scalp hair is in this phase of growth at any given time. Now the follicle lining is all that temporarily anchors the hair in place. Eventually the hair will work its way free and the hair will be shed. Within weeks, a new hair shaft will begin to emerge and the cycle begins again.
Significance of the Bulge
It's all about the stem cellsEarly researchers theorised that hair grew back from the root or bulb of the hair and that destroying the root would destroy the hair forever. Scientific trials have demonstrated that damaging the root and its blood supply does not destroy the follicle's ability to regenerate a hair. It merely delays the process until the body repairs the blood supply to the follicle.
With the discovery of the role of stem cells, later researchers went looking for stem cells in the root of the hair at the base of the follicle. Instead, they found them in the bulge located half way up the follicle. Significantly for successful treatment methods, the bulge is transparent and has no contact with the hair for most of the growth cycle. This is why laser treatment may severely damage the hair root but will pass through the bulge having no effect on it.
Why Galvanic Electrolysis is permanentIn galvanic electrolysis, a small electric current passes through a thin metal probe into the hair follicle. This converts salty water in the follicle into sodium hydroxide using the electrochemical effect called electrolysis. This sodium hydroxide is able to completely destroy the contents and lining of the follicle. Most importantly, it destroys the bulge and its stem cells responsible for producing new hairs. The probe is then removed along with the hair and the follicle contents. This is how electrolysis achieves permanent hair removal.
Because sodium hydroxide is able to circulate throughout the follicle, it is able to destroy all its contents from top to bottom. Unlike other treatments, including other forms of electrolysis, galvanic electrolysis is effective in every stage of hair growth.
Why Thermolysis is not as effective as ElectrolysisIn Thermolysis (known commonly as single needle electrolysis) a small probe inserted into each follicle transmits microwave radiation down to the root of the hair. This radiation works on the same principle as a microwave oven and heats the hair root to about 48°C to 50°C. This rapid increase in temperature causes coagulation of the proteins within the cells, effectively cooking them and killing the hair root.
With Thermolysis, heat concentrates around the root and not at the level of the bulge. The only time that Thermolysis can be permanently effective is usually during early anagen stage when the hair root rises to be adjacent to the bulge. During this brief time, the bulge connects to the hair root and heat in the root conducts to the bulge with the ability to damage or destroy it. This robs the follicle of its ability to grow another hair.
In practice, around 90% of Thermolysis treated hairs will have regrown after 3 months and perhaps 10% permanently destroyed. This means going back over the same hairs, time and time again, thinning them out by 10% at each treatment because the bulge and its stem cells are not in contact with the hair itself and remain immune to the heat produced by Thermolysis.
Why Laser and IPL are not as effective as ElectrolysisLaser and IPL have similar limitations to Thermolysis as they are simply using light to heat the hair instead of microwaves. For this reason, the Therapeutic Goods Administration (TGA) in America only permits Laser and Thermolysis to describe themselves as “permanent hair reduction”. These results from Laser are because the bulge and its stem cells are relatively transparent and therefore immune to heating by laser light or are rarely in contact with the hair to be heated by microwave.
"Permanent hair reduction" is achieved during early anagen stage when the bulge is connected with the hair root and heat from the Laser or microwave is conducted from the root to the bulge with the ability to damage or destroy it and robbing the follicle of its ability to grow another hair.