Latin areola mammae FMA 67796 | TA A16.0.02.012 | |
 | ||
In anatomy, the areola (/əˈriːələ/ or /ɛriːˈoʊlə/) is a small circular area on the body with a different histology from the surrounding tissue. The term is most commonly used to denote the pigmented area on the human breast around the nipple (areola mammae) but it can also describe other small circular areas such as an inflamed region of skin.
Contents
The plural of areola is areolas or areolae, which is pronounced /əˈriːəliː/ or /əˈriːəlaɪ/. "Areola" is the diminutive of Latin area, "open place".
Human mammary areola
Careful inspection of a mature human female nipple will reveal several small openings arranged radially around the tip of the nipple (lactiferous ducts) from which milk is released during lactation. Other small openings in the areola are sebaceous glands, known as Montgomery's glands (or glands of Montgomery). These can be quite obvious and raised above the surface of the areola, giving the appearance of "goose-flesh".
Colour
The areolae can range from pink to red to dark brown or nearly black, but generally tend to be paler among people with lighter skin tones and darker among people with darker skin tones. A reason for the differing colour may be to make the nipple area more visible to the infant.
Size and shape
The size and shape of areolae are also highly variable, with those of sexually mature women usually being larger than those of men and prepubescent girls. Human areolae are mostly circular in shape, but many women and some men have areolae that are noticeably elliptical.
The average diameter of male areolae is around 28.0 mm (1.1 in). Sexually mature women have an average of 38.1 mm (1.5 in), but sizes range up to 100 mm (4 in) or greater. Lactating women, and women with particularly large breasts, may have even larger areolae. A function of the specialized dermis of the areola is to protect the regular breast skin from wear, cracking, irritation, and/or consequent infections; it is exposed to these risks by the salivary effect of a nursing infant and milk residues adhering to its surface. Another function of an areola is to house slowly-adapting mechanoreceptors that trigger oxytocin excretion during nursing. The size of the areola implies a need to protect a larger area than the nipple due to many factors which are not fully known.
Rated according to the Tanner scale of physical development, in stage four, the areolae are raised. In stage five, they are no longer raised.
Mechanoreceptors
Suckling by the baby innervates slowly-adapting 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.