Each breast has 15 to 20 sections, called lobes, that are arranged like the petals of a daisy. Each lobe has many branching ducts which end in dozens of tiny bulbs or lobules that can produce milk.
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. There are no muscles in the breast, but muscles lie under each breast and cover the ribs. Each breast also contains blood vessels and vessels that carry lymph. The lymph vessels lead to small bean-shaped organs called lymph nodes, clusters of which are found under the arm, above the collarbone, and in the middle of the chest. Click here to view the Online Resources page of this web.