Page 156 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
Visible anagen hairs occur only in the A5 and A6 stages – before then, they are within the dermis
and not visible to the naked eye. All other visible hairs are in either catagen or telogen phase.
Figure 87 - The development of the follicle from telogen through all six anagen stages
Catagen Phase
The catagen phase typically lasts for around 2 weeks in most people. During this time the follicle enters an ‘involutionary’ phase when the follicle essentially dies! The dermal papilla separates from the matrix and the hair starts to rise in the follicle. At this time the hair held in the follicle by the cells of the inner root sheath and receives its nourishment from the follicle wall.
There are eight different stages in the catagen phase, including apoptosis (programmed cell death) of many cells throughout the follicle structure. The entire follicle essentially collapses reducing its size considerably, leaving behind an epithelial strand. This strand shortens reaching up to the insertion point of the pilo-muscle. The connection to the dermal papilla is broken leaving the follicle with no blood supply.
Figure 88 - During catagen extensive apoptosis takes place as the follicle regresses towards the skin surface. A club hair begins to form and the DP reduces in size. The bulb region de-pigments – making it a poor absorber of red light.
________________________________________________________________________ 156 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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