Sebaceous Gland Structure and Role in Human Skin

Sebaceous glands are microscopic organs located in the skin secreting an oily substance called sebum that helps with lubricating and waterproofing the skin. They are part of the integumentary system including your hair, nails, and other essential structures that help protect your body from environmental damage. These glands are also part of the pilosebaceous unit comprising the hair follicle, hair shaft, and arrector pili muscles.

To know what are Sebaceous glands we need to have a complete understanding of the sebaceous meaning. According to the Harvard Medical School, 'sebum is a complex mixture of fatty acids, sugars, waxes and other natural chemicals forming a protective barrier against the water evaporation.' So if you have oily skin, your skin is producing an excess amount of the mixture of lipids and cholesterol. These oil glands further make your skin look oily which can create skin issues later.

Physiology of the Sebaceous Gland

The Pilosebaceous Compartment

The sebaceous gland is associated with the hair follicle forming the pilosebaceous unit. Located in the dermis, the sebaceous gland is connected directly to the hair follicle using the excretory duct.

Sebocytes

Sebocytes are the cells that consist of a vital part of the sebaceous gland. Sebocytes are responsible for the synthesis and secretion of sebum. This type of sebaceous gland is divided into three parts-

1. In the Peripheral Zone, these cells are located around the periphery of the sebaceous gland and work on forming a monolayer. These cells are characterized by a flattened appearance. During the process of differentiation, these cells start a slow process of apoptosis and become filled with lipids.

2. The maturation zone is processed when the Sebocytes increase in different volumes and express the specific markers of the maturation like Fatty Acid Dessaturase.

3. Necrosis Zone once mature, the Sebocytes release their sebum content by the holocrine process during which the release of sebum occurs via rupture of the Sebocytes membrane.

Location of the Sebaceous Glands 

Sebaceous glands are located in different parts of the body. However, they are grouped around the hair follicles. The human body, face, and scalp contain the highest concentration of glands. In fact, there are around 900 sebaceous glands. Similarly, shins and other smooth areas carry fewer glands. Palms on your hands and soles of your feet carry no glands.

The Purpose of Sebaceous Glands:

Sebaceous and sweat glands, depending on the location work together with the sweat-producing eccrine glands to regulate body temperature. In cold temperatures, the sebum will have more lipids to shield hair and skin against moisture. In addition to maintaining the moisture, and regular temperature, sebum contains squalene.

Development of Glands

Sebaceous glands are visible between 13 and 16 of felt development emerging from the same stem cells giving rise to the outermost layer of the skin. This is called the epidermis. After this brief period, the production of sebum will steadily increase and reach the apex during puberty in both boys and girls.

However, at the age of 20 or post, the development of sweat and sebaceous glands or sebum slows down and diminishes as we get older. During this situation, the skin turns drier and loses elasticity.

The production of sebum is majorly controlled by various mechanisms like:

Hormone Regulation:

This is the major pathway when it comes to regulating sebum production by Sebocytes. The sebum production regulation takes place by the growth of hormones including insulin, including IGF (Insulin Growth Factor), or hydrocortisone.

Endogenous Factors

This happens when the lipogenic activity gets influenced by other non-hormonal endogenous lipogenic factors including fatty acid metabolism.

Role in Pimples

Most people associate the condition of sebaceous glands with pimples. Although the pores of the skin are like self-cleaning machines, accumulation of dirt or debris combines with sebum for creating a glue-like compound. Once the blocked bacteria like Staphylococcus aurous and Propionibacterium acnes begin multiplying, we tend to recognize pimples. This colonization of bacteria further triggers the immune response.

How to Reduce Sebum Production?

The best way to overcome sebum production is by talking to your doctor. Females are usually advised for medication having the mixture of estrogen and progestin that will help in reducing the production of sebum. In case of severe acne in any part of the body, the doctor may prescribe isotretinoin. Consuming this oral medication will also help in lowering the production of sebum.

Doctors recommend consuming the right diet and avoiding food items that are linked with excess oil production and acne.

Always switch to the products that are chemically linked and cause irritation. If you are not a fan of applying moisturizers then start applying because these creams are really helpful to keep skin healthy and oil-free.

Although sebum or the sebaceous glands are an essential part of the skin, overproduction can lead to skin issues. If you are dealing with cracked skin, or too oily it is best to connect with the specialist to understand the nature of these glands and how you can overcome this issue.