Editing Breast (section)

===Puberty===
[[File:Female breasts five Tanner stages.jpg|thumb|Breast development in puberty is measured with the five-stage Tanner scale]]

The morphological structure of the human breast is identical in males and females until [[puberty]]. For pubescent girls in thelarche (the breast-development stage), the female [[sex hormone]]s (principally estrogens) in conjunction with [[growth hormone]] promote the sprouting, growth, and development of the breasts. During this time, the mammary glands grow in size and volume and begin resting on the chest. These development stages of [[secondary sex characteristic]]s (breasts, pubic hair, etc.) are illustrated in the five-stage [[Tanner scale]].<ref name="A.R.Greenbaum">{{cite journal |vauthors = Greenbaum AR, Heslop T, Morris J, Dunn KW |title = An Investigation of the Suitability of Bra fit in Women Referred for Reduction Mammaplasty |journal = British Journal of Plastic Surgery |volume = 56 |issue = 3 |pages = 230–6 |date = April 2003 |pmid = 12859918 |doi = 10.1016/S0007-1226(03)00122-X }}</ref>

During [[thelarche]], the developing breasts are sometimes of unequal size, and usually the left breast is slightly larger. This condition of asymmetry is transitory and statistically normal in female physical and sexual development.<ref name="asymmetry">{{cite journal |author = Loughry CW |title = Breast Volume Measurement of 598 Women using Biostereometric Analysis |journal = Annals of Plastic Surgery |year = 1989 |volume = 22 |issue = 5 |pages = 380–385 |doi = 10.1097/00000637-198905000-00002 |pmid = 2729845 |display-authors = 1 |last2 = Sheffer |first2 = Daniel B. |last3 = Price |first3 = Thomas E. |last4 = Einsporn |first4 = Richard L. |last5 = Bartfai |first5 = Ronald G. |last6 = Morek |first6 = Wayne M. |last7 = Meli |first7 = Nancy M. |s2cid = 8713713 }}</ref> Medical conditions can cause overdevelopment (e.g., virginal breast hypertrophy, [[macromastia]]) or underdevelopment (e.g., [[tuberous breast deformity]], [[micromastia]]) in girls and women.

Approximately two years after the onset of puberty (a girl's first [[menstrual cycle]]), estrogen and growth hormone stimulate the development and growth of the glandular fat and suspensory tissues that compose the breast. This continues for approximately four years until the final shape of the breast (size, volume, density) is established at about the age of 21. [[Mammoplasia]] (breast enlargement) in girls begins at puberty, unlike all other primates, in which breasts enlarge only during lactation.<ref name="stoppler" />