Sebaceous glands are scattered over the entire surface of the skin, except for the palms of the hands and the soles and sides of the feet. The simple branched areolar glands exude an oily substance known as sebum. Sebum is usually secreted onto the hair shaft, but in a few regions of the body it is directly emitted onto the surface of the skin. A natural skin softener, sebum helps keep hair from becoming brittle and skin from becoming dry and rough. Sebum also contains a bactericidal agent that inhibits the growth of a variety of bacteria