Macrophotograph of the skin on the back of the hand of a young male human showing details of patterns in the outer cornified (keratinised) epidermis. The skin surface shows erectile hairs, which with sweat glands & blood capillaries form part of the temperature- regulatory mechanism of the body. Hairs are produced by hair follicles, which are cylindrical downgrowths of the surface epithelium ensheathed by connective tissue. A bundle of smooth muscle, the arrector pili muscle, is attached to the connective tissue sheath of each follicle. When contracted, the hair stands on end & its point of insertion is pulled down causing the effect known as goose-flesh"."