There are a number of both essential and non-essential skin appendages. The essential ones include the various glands, and the non-essential ones, the hair and nails. The sebaceous glands are a group of specialized cells in the basal layer of the epidermis which produces sebum. This is an important fatty secretion which is discharged onto the skin surface through a small duct leading into the hair follicle opening. Sebum has a number of functions, one of which is to lightly coat the epidermis with oil and so help retain moisture in the skin. Another is to improve the pliability of the skin. It also has a mild anti-bacterial and antifungal action. Sebaceous glands occur over the whole skin surface, except on the palms of the hands and soles of the feet. They are most numerous on the face and scalp. The activity of these glands varies greatly between individuals and at various ages. During adolescence there is usually an over-production of sebum, resulting in acne, whereas in the elderly there is an under-production, resulting in dry. non-pliable skin.

Apocrine glands are modified sebaceous glands, found mainly in the armpits, genital area, and around the nipples. They are specialized glands which do not function until after puberty. They are stimulated by certain hormonal factors (such as the hormonal changes which occur during menstruation and pregnancy) and emotional factors (such as stress and sexual arousal). Their secretions are responsible for an individual’s characteristic odour and may also have some minor lubricating function.

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