From puberty to menopause, a woman's breasts undergo almost daily changes based on normal hormone cycles. Hormones influence the outward appearance of the breast and contribute to microscopic changes internally. By becoming familiar with your own breasts and understanding the normal changes they undergo, you can better detect lumps or unusual changes and alert your physician.
During puberty, estrogen production and growth in the glands is the major influence on breast growth. Breast development is completed after ovulation begins to occur regularly in the teen years. Most women notice cyclical changes to their breasts due to fluctuations in hormones. These affect the size, firmness and tenderness of the breasts. Before menstruation, for example, the breasts may swell and become tender.
During pregnancy, hormones prepare the breasts for milk production. The growth of the mammary glands and ducts produces swelling of the breasts. Veins in the breasts may appear on the surface of the skin, which has stretched to accommodate development of internal breast glands. As women go through menopause, mammary glandular tissue is replaced largely by fat, which could change the size and appearance of the breasts.
Parts of the Breast
The breast has three major parts:
- Fibrous tissue provides support for the breast. It separates the breast into segments and extends from under the skin's surface to the chest wall. Younger women have more fibrous tissue and firmer breasts than older women.
- Mammary glands are the part of the breast that produce milk. Each breast has 15 to 20 sections or "lobes" that are arranged like the petals of a daisy. Each lobe has smaller lobules that end in dozens of tiny milk-producing bulbs. The lobes, lobules and bulbs are linked by thin tubes called ducts that carry milk from the lobes to the nipple.
- Fat tissue fills the spaces between the other parts of the breast and forms a covering for the breast. Age and weight influence the amount of fat found in the breast. After menopause, fat tissue replaces the mammary glands and breasts lose their firmness.