Hair
The hair grows from the cells of the hair bulb, which is nourished by the hair papilla. The cells that make up the keratin of hair are among the fastest dividing cells in the body. The hair is pushed outwards by the constant cell division in the area of the hair bulb.
The hair gets its colour from melanin, which is formed by the melanocytes. We can understand the hair root as a tubular invagination of the epidermis into the corium. The hair formation is a modified horn formation.