Each breast has 15 to 20 sections, called lobes, that are arranged like the petals of a daisy. Each lobe has many smaller lobules, which end in dozens of tiny bulbs that can produce milk. The lobes, lobules, and bulbs are all linked by thin tubes called ducts. These ducts lead to the nipple in the center of a dark area of skin called the areola. Fat fills the spaces between lobules and ducts.
Normal Breast Development
Breast development is a normal part of development in the human female.
Breast development occurs in distinct stages, first before birth, again at puberty and is complete during the childbearing years. Changes occur to the breasts during menstruation and when a woman reaches menopause.
The development and kinds of breast changes that take place are directly related to age. There are three phases of development: lobule development, which takes place between the ages of 10 and 25; glandular development, which is under the influence of menstrual hormones and occurs between the ages of about 10 and 45, and involution, or shrinkage of the milk ducts, which begins from about age 35 on.