What Are Pores For, and What Different Types Are There?

Depending on the secretory glands to which they are connected, there are different types and functions of pores.

• Sebaceous pores

  As their name suggests, these pores distribute sebum over the surface of the epidermis to moisturize the skin. They are located all over the body, with a few exceptions like palms, soles, sides of fingers and toes, glans and prepuce, labia minora and inner surface of labia majora. Sebaceous pores are connected to the sebaceous glands. The latter are generally attached to the hair (hair follicles), but as mentioned, there are a few areas where they are not present. The lips, the nipple areola and the eyelids are among these areas, too. The size of the sebaceous glands is inversely proportional to that of the hair.Sweat pores

  These pores evacuate the sweat produced by the eccrine sweat glands, and are not visible to the naked eye. They cover virtually the entire body (except the genitals), and are not attached to hair follicles. They are most abundant on the palms and soles of the feet, and abundant on the back, armpits and scalp.

Note: On the face, the visible pores that are sometimes referred to as “dilated” are, in fact, the sebaceous pores. Pores corresponding to sweat glands, on the other hand, are not visible to the naked eye.

The main of function of pores is to ensure exchanges between skin cells and the external environment. They help eliminate substances secreted by the skin, such as perspiration (sweat pores). They also evacuate dead skin cells (sebaceous pores).

The sebaceous pores also supply nutrients to the skin's constituents. This is particularly the case for skincare ingredients with moisturizing, nourishing and antioxidant properties. Pores also oxygenate cells.

Pores can become unsightly when dilated or large, giving the appearance of uneven skin texture. This phenomenon corresponds to the opening and increased volume of pores, making them more visible. The dilation of sebaceous pores is the result of various factors.

• Accumulation of pollution in the pores.

• Excessive sebum production (seborrhea) correlated with an accumulation of the keratin lining the cavity. This can create a “plug”, called a comedo, which can oxidize and form a blackhead.

• Use of unsuitable cosmetics, such as comedogenic products.

• A diet too rich in fat and sugar.

• Smoking.

• Excessive consumption of alcoholic beverages.

• Skin aging. This is a lesser-known cause, yet it is an important one. Remember that the skin is supported by a dermal network of fibrous proteins (collagen elastin) which give it its firmness and elasticity. As we age, the production of these proteins slows down, the skin sags and the sebaceous pores cannot maintain their shape. They slowly succumb to gravity, stretching a little further over time. 

Note: Pore action thus influences skin type, with dilated pores often synonymous with oily skin.

• Structure des annexes cutanées, Comprendre la peau, Histologie et histophysiologie de la peau et de ses annexes, Ann Dermatol Venereol, (2005)