Hair Follicle
The hair follicle is a dynamic and living component, unlike the hair shaft. At its base lies the papilla, which is responsible for supplying blood to the cells through tiny capillaries. Adjacent to the papilla is the germinal matrix, which plays a crucial role in supporting hair growth by facilitating the development of new cells. The papilla and germinal matrix are encompassed by a bulb that contains hormones that affect the structure and growth of hair. Safeguarding and directing the hair shaft as it emerges from the bulb is the root sheath, consisting of both an inner and outer layer.
The Anatomy of the Root Sheath and Exterior Structures
Within the protective root sheath, there are two sheaths present. The inner sheath consists of three layers. The innermost layer contains cells that point downwards and slightly inwards, enabling them to establish a connection with the cells of the hair shaft cuticle. Moving outward, we have Huxley’s layer and Henle’s layer, which make up the middle and exterior layers of the inner sheath, respectively.
Additionally, the outer root sheath envelops the inner sheath and is responsible for connecting with the sebaceous glands in the skin. These glands produce sebum, an oil that plays a vital role in lubricating and waterproofing both the hair and the skin. Apart from these components, the hair follicle also includes the vitreous layer, the fibrous root sheath, the suprabulb region, the isthmus, and the infundibulum.