The hair shaft is composed of three concentric layers, namely the outer cuticle, middle cortex, and inner medulla^{1 2 3}. The cuticle forms the outer surface of the hair shaft and is the hair’s outer protective layer^{1 2}. Cells in the hair matrix surrounding the dermal papilla are responsible for hair growth¹. The strength, color and texture of a hair fiber are provided by the cortex layer of the hair shaft³. The only living cells of a hair are in and near the hair bulb⁴.