Page 108 - Blog Posts v1

Catagen
During catagen, the hair growth and melanin production stop abruptly. The lower part of the follicle undergoes a period of apoptosis – the cells die! At the same time, the base of the follicle moves towards the skin surface.
This phase typically last between 10 to 14 days in humans, for all hairs.
Telogen
This is commonly known as the ‘resting’ phase. During this time there is no growth or melanin production. The germ cells become essentially dormant and the follicle is quiescent.
This phase can last anywhere between 6 weeks and 6 months, depending on the body site.
Early Anagen
In the late telogen phase, the germ cells begin to proliferate near the ‘bulge’ region of the arrector pili muscles. This results in the formation of new follicular matrix cells and new melanocyte activity. A new hair bud begins to form, which ‘pushes’ the old hair out of the follicle, as it grows upwards.
Clinical studies (see the references below) reveal that the melanin pigment distribution in the hair shaft is critical in achieving destruction of the follicular germ cells. This is why laser/IPL hair removal only works successfully on pigmented hair, and ONLY in the anagen phase when the hair shafts and follicles are fully pigmented.
The extent of follicular damage depends strongly on the fluence applied (energy density). Lower fluences result in ‘delayed growth’ of follicles, while higher fluences can permanently destroy them. This is closely tied into the pulse duration (how long each light pulse is). Longer pulses result in more ‘cooking’ of the follicles and hence the stem cells. If these cells
Mike’s Blog Posts 108