Page 154 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
The Hair Growth Cycle
Hair growth is a continuous cyclic process which may be affects by the owner’s hormones, age and nutrition. The cycle consists of four main stages –
Anagen Phase
During anagen the follicle enlarges and returns to its original shape. The anagen stage can be sub-divided on to six distinct phases – during stages A1 to A5, the stem cells proliferate and migrate down the follicle to enclose the dermal papilla. They then begin to grow cells for the hair shaft and the inner root sheath. Only in stage A5 does the new hair shaft begin to become visible above the skin surface.
Melanocytes in the hair matrix produce new melanin cells which populate the growing hair shaft. In stage A5 the hair bulb and papilla are fully grown and the new hair begins to appear above the skin surface. A number of regulatory proteins are thought to be required for the anagen phase including vascular growth factor (VEGF), fibroblast growth fact (FGF), hepatic growth factor (HGF) and insulin-like growth factor (IGF-1).
Figure 86 – The hair growth cycle
Towards the end of the anagen stage thinning and lightening of the pigment at the base of the hair shaft takes pace, and melanin production stops. Melanocytes reabsorb their dendrites. During anagen the follicle receives its nourishment through the dermal papilla.
________________________________________________________________________ 154 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
© The Laser-IPL Guys, 2025
Anagen
Growth
Catagen
Regression
Telogen
Resting
Exogen
Shedding