Areola

Areola and breast diagram

The human areola (areola mammae) is the pigmented area on the breast surrounding the nipple. More broadly, an areola refers to a small circular area on the body that has a different histology from the surrounding tissue, or to other small circular areas, such as an inflamed region of skin.

The mature human female nipple has several small openings arranged radially around the tip of the lactiferous ducts, from which milk is released during lactation. The other small openings in the areola are sebaceous glands, also known as areolar glands.

Shade

The areolae can range in color from pink to red to brown to dark brown or nearly black, but they generally tend to be paler among individuals with lighter skin tones and darker among those with darker skin tones. One reason for the varying colors may be to make the nipple area more visible to infants.

Hyperpigmentation occurs in most women during the second stage of pregnancy, resulting in a temporary darkening.

Size and Shape

An elliptical female breast. The size and shape of areolae and nipples can vary significantly, with those of women typically being larger than those of men and prepubescent girls. Human areolae are generally circular in shape, but many women exhibit larger areolae that are distinctly elliptical.

The average diameter of male areolae is approximately 28.0 mm (1.1 in). Sexually mature women have an average diameter of 38.1 mm (1.5 in), but sizes can exceed 100 mm (4 in). Lactating women and those with particularly large breasts may have even larger areolae. A function of the specialized dermis of the areola is to protect the surrounding breast skin from wear, cracking, and irritation. Infants sometimes cause trauma to the nipple and areolae by latching on.

According to the Tanner scale of female physical development, the areolae enlarge during stage 3, but there is no separation of contour. In stage 4, the areolae and papillae rise above breast level and form secondary mounds. By stage 5, the breasts are fully developed, resulting in a recession of the areolae, with the papillae sometimes extending slightly above the contour of the breasts.

Pregnancy can cause enlargement of the areola tissue and the Montgomery glands or tubercles.

Mechanoreceptors Breastfeeding by the baby stimulates slowly and rapidly adapting mechanoreceptors that are densely packed around the areolar region.

Diseases Paget's disease of the breast is a malignant condition that outwardly may have the appearance of eczema, with skin changes involving the areola and nipple.