How does acne develop?

Acne is a skin disorder which is caused by plugged pores on the skin. The underlying reason for the formation of blocked pores is unknown. The thick, oily substance called sebum, which normally drains to the surface, gets blocked and bacteria begin to grow. Both whiteheads and blackheads start out as a microcomedone. Microcomedones become skin blemishes and can form into either a whitehead or a blackhead. When the trapped sebum and bacteria stay below the skin surface, a whitehead is formed. A blackhead occurs when the trapped sebum and bacteria partially open to the surface and turn black due to melanin, the skin?s pigment. Blackheads can last for a long time because the contents very slowly drain to the surface. Blackheads and whiteheads are filled with trapped sebum and bacteria. Sebum production is affected by male hormones called androgens. In unaffected skin, sebum empties onto the skin surface through the opening of the follicle, or pore. Cells which line the follicle are called keratinocytes. With excess sebum production, the cell lining of the follicle wall also starts to overproduce. The additional amounts of sebum combine with dead cells and plug the canal. The bacteria on the skin surface enter these clogged ducts and attract white blood cells. The reaction between white blood cells and the bacteria cause the surrounding area to become inflamed. Acne usually develops over 2-3 weeks before it appears on the surface of the skin. It starts as a blemish in the sebaceous hair follicle.