出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/30 00:17:05」(JST)
| Areola | |
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Close-up of a human female breast showing the areola
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Breast schematic diagram
(adult female human cross section) |
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| Details | |
| Latin | areola mammae |
| Identifiers | |
| Gray's | p.1267 |
| TA | A16.0.02.012 |
| FMA | 67796 |
| Anatomical terminology | |
In anatomy, the areola (/əˈriːələ/[1][2] or /ɛriːˈoʊlə/[2]) 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.
The plural of "areola", is "areolæ"/"areolae", which is pronounced /əˈriːəliː/ or /əˈriːəlaɪ/. "Areola" is the diminutive of Latin area, "open place".
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).[3] These can be quite obvious and raised above the surface of the areola, giving the appearance of "goose-flesh".
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 color may be to make the nipple area more visible to the infant.[4]
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 25 mm (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.[5] Lactating women, or women with particularly large breasts, may have even larger areola. The main function of the specialized dermis of the areola is to protect the regular breast skin from wear, cracking, or irritation and possible infections; it is exposed to these risks by the salivary effect of the nursing infant and milk residues adhering to its surface. The areola's size 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.[6] In stage five, they are no longer raised.[6]
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| リンク元 | 「乳輪」 |
| 関連記事 | 「areola」 |