What breast changes happen at puberty?
As a girl approaches puberty, the first outward signs of breast development begin to appear. When the ovaries start to secrete estrogen, fat in the connective tissue begins to accumulate causing the breasts to enlarge. The duct system also begins to grow. Usually, the onset of these breast changes is also accompanied by the appearance of pubic hair and hair under the arms. Once ovulation and menstruation begin, the maturing of the breasts begins with the formation of secretory glands at the end of the milk ducts. The breasts and duct system continue to grow and mature with the development of many glands and lobules. The rate at which breasts grow varies greatly and is different for each young woman. Generally, there are five stages of breast development in girls.
