What is the tube-like depression that contains the hair root called?

The tube-like depression that contains the hair root is known as the follicle. The follicle serves as the structure from which the hair grows, providing the necessary environment and nutrients for the hair to develop and strengthen. This structure is located deep within the skin and is crucial for the hair growth cycle.

Within the follicle, several other components play important roles, such as the bulb, which is the rounded part at the base of the follicle where hair cells multiply, and the papilla, which contains blood vessels that supply nutrients to the hair. The medulla, on the other hand, refers to the innermost layer of the hair shaft itself, rather than a structural component surrounding the hair root. Understanding the follicle's role in hair growth helps in comprehending various aspects of hair care and treatments within cosmetology.