Sebum is produced by sebaceous glands. These are found over most of the body, although there are few on the hands or feet and none on the palms and soles. They are also numerous in the ear canal and around the genitals. The sebaceous gland consists of lobes connected by ducts, which are lined with cells similar to those on the skin surface.
Most sebaceous glands open out into the hair follicle.
Some free sebaceous glands open directly onto the skin surface. These include Meibomian glands on the eyelids, Tysons glands on the foreskin and Fordyces spots on the upper lip. Sebum is produced when the sebaceous gland disintegrates. The cells take about a week from formation to discharge. These glands are in turn under the influence of the pituitary gland, located in the brain.