The dermal papilla is primarily responsible for stimulating hair growth by delivering a constant supply of blood and nourishment to the hair root, according to Follicle.com. Vital for hair growth and located at the base of the hair follicle, the papilla also contains androgen-sensitive hormone receptors. Since androgen or male hormones play a role in hair growth, these receptors help regulate the rate or speed of growth.
A vascular, bulb-shaped structure, the papilla fits snugly into the base or root of each hair strand, as explained by Follicle.com. The papilla supplies hair with nourishment during active growth phases and rests when hair sheds and stops growing. Without the blood, oxygen and nutrients supplied by the papilla, hair growth would be impossible. The papilla is also responsible for transporting protein cells, the building blocks of hair, to the growth site.
According to Follicle.com, the hair-growth cycle has three phases: anagen, catagen and telogen. During the anagen, or growth, phase, hair grows at a rate of approximately one-half inch per month. At this time, the papilla is actively supporting hair growth. During the catagen, or transitional, phase, the follicle shrinks, allowing the dermal papilla to separate from the hair root, which results in shedding. During the telogen, or resting, phase, the papilla is inactive.