The mass of epidermal cells that form a small tube or canal is called a "hair follicle." Hair follicles are structures found in the skin and are responsible for producing hair. They are composed of epidermal cells that extend into the deeper layers of the skin and are connected to sebaceous glands and arrector pili muscles. Hair growth occurs when these cells divide and grow, pushing the older cells up and out of the follicle, forming the visible hair shaft.