The growth phase of hair is known as the:

• A. Anagen phase
• B. Catagen phase
• C. Telogen phase
• D. Exogen phase

Answer: (A)

The growth phase is the period of active hair production, when the follicle’s matrix cells divide and push the hair shaft upward so the hair actually lengthens. This phase, called the anagen phase, lasts for as long as the follicle remains actively producing cells, which is why scalp hair can grow quite long. After this comes catagen, a brief transition where growth slows and the follicle shrinks; then telogen, the resting phase where the hair is held in place before shedding; and finally exogen, the shedding phase when the hair is released. Since growth requires ongoing cell division and elongation of the hair shaft, the anagen phase is the best answer.