The outer breast consists of a nipple and areola. The tip of the nipple contains several hole openings allowing for milk to flow through during lactation. The areola is the pigmented area around the nipple. It is covered with Montgomery glands that secrete oil to lubricate the nipple and areola.
The primary function of female breasts is to produce milk in order to nourish an infant, a process called lactation. The breasts, which are composed primarily of fatty tissue, also contain milk producing glands called lobules. Lobules are connected to the nipple by a network of tubes called milk ducts. The breasts produce milk from water and nutrients removed from the bloodstream. The milk is stored in the lobules until the hormone oxytocin signals the tiny muscles in the lobules to contract, and push the milk through the ducts. This process is called let-down reflex or the milk-ejection reflex.
The infant's suckling draws milk from the nipple. The size of a breast is determined more by the amount of fatty tissue in the breast than the amount of secretory tissue, so breast size has little to do with the ability to produce a sufficient amount of milk. All aspects of breast development and function are influenced by hormones. Prior to puberty, there is little difference between the male and female breast. As a girl enters puberty, the hormones estrogen and progesterone cause the breasts to undergo significant changes, eventually leading to the development of mature female breasts.
