The nail body appears pink because of the rich bed of capillaries in the underlying dermis. The nail matrix contains rapidly dividing epithelial cells. As the nail cells are produced by the matrix, they become heavily keratinized, and the nail body slides distally over the nail bed. The average growth rate of fingernails is 1 mm per week, but the growth rate is somewhat slower in toenails. The sebum contains fats, cholesterol, proteins, salts, and dead cell fragments.
Sebum softens and lubricates the skin, making it more pliable.
It prevents hair from becoming dry and brittle, and it prevents water loss from the skin when the external humidity is low. The sebum also inhibits bacterial growth on the skin. The sebaceous glands are found all over the body, except on the palms of the hands and soles of the feet. They are small on the body trunk and limbs, but quite large on the face, neck and upper chest. The exact composition depends on heredity and diet.