What is the term for the bottom of the hair follicle where cells divide and produce new hair cells?

The term that accurately describes the bottom of the hair follicle where cells divide and produce new hair cells is known as the matrix. The matrix is a critical area within the hair follicle, specifically located at the base, and is composed of rapidly dividing keratinocytes. These cells differentiate and keratinize as they move upward through the hair follicle, ultimately forming the hair shaft. The matrix plays a vital role in hair growth and is essential for the production of new hair strands.

Other terms in the list refer to different aspects of the hair follicle structure. The follicular bulb is often used to describe the region enclosing the lower portion of the hair follicle, but it does not specify the area where cell division occurs. The dermal papilla is located at the base of the hair follicle and contains blood vessels that supply nutrients to the hair, but it is not directly where new hair cells are produced. The root sheath encompasses the hair, providing structure to the follicle but does not involve the active production of hair cells. Thus, the matrix is the most accurate answer in describing the site of cell division and hair growth.