Mitotic cells in the hair begin their growth activity in the?

• A. Matrix
• B. Cortex
• C. Medulla
• D. Cuticle

Answer: (A)

Growth starts in the hair matrix, the growth zone at the base of the hair follicle where cells are actively dividing. These mitotic cells multiply and then differentiate to form keratinocytes that will become the hair shaft and its surrounding structures. As they move outward from the matrix, they keratinize and organize into the hair’s layered architecture.

The other components—cortex, medulla, and cuticle—are parts of the hair shaft itself. They are formed by cells produced in the matrix and then specialized as they travel upward, but they are not sites where new cells divide. The cortex makes up the main body of the hair, the medulla is the inner core in some hairs, and the cuticle is the outer protective layer.