Which of the following provides the blood supply that is vital to the growth the hair?

• A. Hair shaft
• B. Cuticle
• C. Cortex
• D. Dermal papilla

Answer: (D)

The essential factor for hair growth is the blood supply provided by the dermal papilla. This structure sits at the base of the hair follicle and contains a network of capillaries that deliver oxygen and nutrients to the hair matrix, the region where new hair cells are produced. Those nourished cells then keratinize and form the hair shaft, including the cortex and cuticle as they grow outward. Without the dermal papilla’s blood supply, the matrix wouldn’t have the resources it needs to continuously produce hair, so growth would slow or stop. The hair shaft, cuticle, and cortex themselves are parts of the hair, not providers of nourishment; they depend on the dermal papilla for their growth.