Comedones:Comedones are the plural form of comedo, which is the primary indicator of acne. They consist of an enlarged pore filled with skin debris, bacteria, and oil (sebum). Comedones can be either closed or open. A closed comedo has a blocked skin opening, potentially leading to a mild inflammatory reaction in the surrounding area, and is commonly referred to as a whitehead. On the other hand, an open comedo features a wide skin opening with a darkened mass of debris on top, known as a blackhead.Acne develops when the sebaceous glands in the skin begin producing oil during puberty. These glands are activated by male hormones that are produced in the adrenal glands of both boys and girls. The oil serves to lubricate and protect the skin. However, certain conditions can cause cells near the sebaceous gland openings to block these exits, resulting in an accumulation of oil beneath the skin. Bacteria, which are usually harmless residents of the skin, thrive on this oil, proliferate, and cause inflammation in the surrounding tissue once the follicle ruptures.If this inflammation occurs close to the surface, a pustule forms; if it's deeper, it results in a papule or pimple; and if deeper still, it can develop into a cyst. When the pore is entirely closed to the surface, a whitehead forms. If the pore is wide open, the oil is exposed to air, becomes oxidized, and turns black, resulting in a blackhead. This explains how the two types of comedones are formed.The term comedo originates from the Latin word for glutton, as ancient beliefs held that the contents of a comedo were remnants of a gluttonous worm. The preferred plural form of comedo is comedones.