Areola

Areola

In anatomy, an areola, plural areolae, (diminutive of Latin area, "open place") is any circular area such as the colored skin surrounding the nipple. Although the term is most commonly used to describe the pigmented area around the human nipple (areola mammae), it can also be used to describe other small circular areas such as the inflamed region surrounding a pimple. One reason the color of the areola differs from that of the rest of the breast is that the areola roughly delineates where the ducts of the mammary glands are. Careful inspection of a mature human female nipple will reveal several small openings arranged radially around the tip of the nipple (lactiferous ducts) from where milk is released during lactation. Other small openings in the areola are sebaceous glands, known as Montgomery's glands (or glands of Montgomery), which provide lubrication to protect the area around the nipple and assist with suckling and pumping of the lactation. These can be quite obvious and raised above the surface of the areola, giving the appearance of "goose-flesh". This tissue, in addition to supporting the flow of milk, also bears the brunt of abuse that the suckling involves. The other reason for its color comes from an abundance of two polymers: eumelanin (the brown pigment) and pheomelanin (the red pigment). The genetically-directed amount of these pigments determines the color of the areola. They can range from pale yellow to nearly black, but generally tend to be paler among people with lighter skin tones and darker among people with darker skin tones. An individual's areolae may also change color over time in response to hormonal changes caused by menstruation, certain medications, and aging. Most notably, the areolae may darken substantially during pregnancy – some regression to the original color may occur after the baby is born, but again, this varies from individual to individual.

references: http://en.wikipedia.org/wiki/Areola