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Human Hair Growth Cycle
Typically, hair growth within each follicle occurs in a cycle.
There are three stages of the hair growth cycle: anagen, catagen and telogen.
Anagen is the phase where the actual hair fiber is produced. In this mature state of proliferation and differentiation,
the hair follicle consists of a total of eight concentric layers and melanogenesis occurs within pigmented hair follicles.
Anagen is followed by catagen, a period of controlled regression of the hair follicle. Ultimately, the hair follicle enters
the telogen stage where the follicle is in a so-called resting state.
This diagram shows the regression of a mature anagen hair follicle. Upon entering the catagen stage, the dermal papilla
condenses as the cells become inactive.
With a lack of papilla cell stimulation, the hair fiber and root sheaths stop growing.
The dermal papilla can become isolated in the dermis and the hair fiber can get pulled out by combing, shampooing or brushing.
Anagen is the longest phase, with up to 90% of follicles on a normal human scalp during this active hair growth stage at any given time.
Correspondingly, telogen hair follicles comprise up to 10% of the follicles on the scalp.
The length of the anagen growth phase for scalp hair is usually 6-10 years, while telogen lasts just 30-90 days and catagen is
estimated to last 14-21 days.
The Hair Starter System grows Mature Anagen.
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