| Developmentally, initially hair is white. The natural | | | | self-maintenance of melanocyte stem cells. |
| color of hair derives from a type of pigment | | | | As the hair is being formed, melanocytes inject |
| called melanin that begins to form before birth. | | | | pigment (melanin) into cells containing keratin. |
| The natural color of our hair depends upon the | | | | Keratin is the protein that makes up our hair, skin, |
| distribution, type, and amount of melanin in the | | | | and nails. Throughout the years, melanocyctes |
| middle layer of the hair shaft or cortex. | | | | continue to inject pigment into the hair’s |
| Hair has two types of pigments: dark (eumelanin) | | | | keratin, giving it a colorful hue. |
| and light (phaeomelanin). They blend together to | | | | With age comes a reduction of melanin. The hair |
| make up the wide range of hair colors. | | | | turns gray and eventually white. |
| Pigmentation is under complex genetic control | | | | The hair follicle has a “melanogentic clock” |
| regulated by more than 150 alleles representing | | | | which slows down or stops melanocyte activity, |
| more than 90 gene loci, with tyrosinase activity | | | | thus decreasing the pigment our hair receives. |
| the rate-limiting step among the | | | | This occurs just before the hair is preparing to fall |
| melanogenesis-related enzymes. The biosynthesis | | | | out or shed, so the roots always look pale. |
| of melanin and its subsequent transfer from | | | | Hair turns gray because of age and genetics, in |
| melanocyte to hair bulb keratinocytes depend on | | | | that genes regulate the exhaustion of the |
| the availability of melanin precursors and on a | | | | pigmentary potential of each individual hair follicle. |
| multitude of signal transduction pathways that are | | | | This occurs at different rates in different hair |
| both highly complex and commonly redundant. | | | | follicles. For some people it occurs rapidly, while in |
| These signalling pathways can be both dependent | | | | others it occurs slowly over several decades. |
| and independent of receptors, act through auto-, | | | | Recent studies show that a failure of melanocyte |
| para- or intracrine mechanisms, and can be | | | | stem cells (MSC) to maintain the production of |
| modified by hormonal signals. Despite many | | | | melanocytes cause the graying of hair. The MSC |
| shared features, follicular melanocytes appear to | | | | reside in the hair follicle and release a multitude of |
| be more sensitive than epidermal melanocytes to | | | | factors that that produce and process the |
| aging influences. This can be seen most | | | | pigments of the hair. Failure of MSC maintenance |
| dramatically in hair greying and this is likely to | | | | results in the breakdown of signals that produce |
| reflect significant differences in the epidermal and | | | | hair color. Dysfunction of the MSC is due to both |
| follicular microenvironments. The hair follicle | | | | intrinsic factors (age, genetic defects, hormones) |
| pigmentary unit may also serve as an important | | | | and extrinsic factors (climate, pollutants, toxins, |
| environmental sensor, whereby hair pigment | | | | chemicals, sun damage). |
| contributes to the rapid excretion of heavy | | | | A & G Hair Complex is a combination of |
| metals, chemicals and toxins from the body by | | | | factors derived from stem cells that mimic what |
| their selective binding to melanin; rendering the hair | | | | the MSC produce. Thus topical application of A |
| fiber a useful barometer of exposures. | | | | & G Hair Complex to the scalp reconditions |
| Melanin is made up of specialized pigment cells | | | | the hair follicle so that all factors required for |
| called melanocytes. They position themselves at | | | | pigmentation of the hair are restored. With the |
| the openings on the skin’s surface through | | | | restoration of the factors to the hair follicle, |
| which hair grows (follicles). Each hair grows from a | | | | normal pigmentation of the hair is restored. |
| single follicle. Hair graying is caused by defective | | | | |