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

The tube-like depression that contains the hair root is called the follicle. The follicle is a vital part of hair growth, anchoring the hair into the skin and providing the necessary environment for the hair to develop. It is responsible for producing the hair and is located within the dermal layer of the skin.

The hair bulb, while related to the follicle, refers specifically to the expanded base of the follicle where cell division occurs to create new hair. The hair shaft is the portion of the hair that is visible above the skin’s surface. The dermal papilla is found within the hair bulb and plays a crucial role by supplying blood and nutrients to the hair follicle, but it is not a tube-like structure that contains the root itself. Thus, the follicle is the correct term for the structure that encases the hair root.