Beg ar vronn : diforc'h etre ar stummoù

[[Image:20060726_supernumerary_nipples_torso_w_text.png|thumb|right|Begoù-bronnoù dreist-kont. A - Dreist-kont. B - Ordinal. C - Dreist-kont]]

[[Image:Nipple piercings.jpg|thumb|Begoù-bronnoù minellet]]

 

 

 

Sometimes, [[baby|babies]] (male or female) are born producing milk. This is called '[[witch's milk]]'; it is caused by maternal [[estrogen]]s acting on the baby and is quite common. Witch's milk disappears after several days.

 

From conception until [[sexual differentiation]], all mammalian [[fetus]]es within the same [[species]] look the same, regardless of sex. In humans this lasts for around 14 weeks after which, [[sex chromosome|genetically-male]] fetuses begin producing male [[hormone]]s such as [[testosterone]]. <ref>{{cite web | url = http://wendyzukerman.wordpress.com/ | title = Nip and Tuck, by Wendy Zukerman | accessdate = 2008-6-6 | language = english | format = html | source = Webblog}}</ref>

Most of the time, males' nipples don't change much past this point. However, some males develop a condition known as [[gynecomastia]], in which the fatty tissue around and under the nipple develops into something similar to a female breast. This may happen whenever the testosterone level drops because of medications.