Tanner Stage 1 (ages 8-11) - the preadolescent breast consists of a small elevated nipple with no significant underlying breast tissue.

Tanner Stage 2 (ages 8-14) - Puberty begins usually between ages of 8 and 13, though the average age is 11, with the development of breast tissue and pubic hair. With the hormonal changes of puberty, breast buds form. This second stage of breast development is the breast bud stage. Here, there is elevation of the breast and nipple as a small mound; the areola begins to enlarge. Milk ducts inside the breast begin to grow.

Tanner Stage 3 (ages 9-15) - in stage 3, there is further enlargement and elevation of the breast and areola (with no separation of their contours) The areola begins to darken in color. The milk ducts give rise to milk glands that also begin to grow.









Tanner Stage 4 (ages 10-16) - next, there is projection of the areola and nipple to form a secondary mound.

Tanner Stage 5 (ages 12-19) - in the mature adult breast, there is a projection of the nipple only; however, in some woman the areola continues to form a secondary mound.











Once menstruation and ovulation begin, the breasts begin to form secretory glands at the end of the milk ducts. Each breast consists of 15 to 20 sections of lobes. Each lobe consists of yet smaller lobules that make up even smaller bulbs referred to as terminal ductal lobular unit. This network of lobes, lobules and bulbs are all interconnected ending in the nipple.

Each month women have a fluctuation in hormones that regulate their menstrual cycle. Estrogen, a hormone produced by the ovaries in the first half of the menstrual cycle, stimulates the growth of milk ducts in the breasts. Increasing levels of estrogen results in ovulation halfway through the cycle. Next, the hormone, progesterone, stimulates the formation of the milk glands. The fluctuation of estrogen and progesterone are hypothesized to be responsible for the cyclical changes i.e. tenderness, increased sensitivity, size fluctuation, swelling, etc. that women tend to experience in their breasts prior to menstruation.

During pregnancy under the influence of progesterone; the follicle stimulating hormone, oxytocin; lutenizing hormone; and human placental lactogen, women begin to notice several changes in their breast. The breast undergo a rapid swelling with increased pigmentation of the areola and a more pronounced nipple. Many women will complain of increased tenderness and sensitivity especially to the outer quadrants of the breasts and the nipple region.

Many physicians believe the breasts are not fully mature until a woman has given birth and produced milk. Breast changes are one of the earliest signs of pregnancy - a result of the pregnancy hormone, progesterone. In addition, the areolas (the dark areas of skin that surround the nipples of the breasts) begin to swell followed by the rapid swelling of the breasts themselves. Most pregnant women experience tenderness down the sides of the breasts and tingling or soreness of the nipples because of the growth of the milk duct system and the formation of the many more lobules.

During pregnancy under the influence of progesterone, follicle stimulating hormone, oxytocin, lutenizing hormone, and human placental lactogen women begin to notice several changes in their breast. The breast undergo a rapid swelling with increased pigmentation of the areola and a more pronounced nipple. Many women will complain of increased tenderness and sensitivity especially to the outer quadrants of the breasts and the nipple region.

By the time a woman reaches her late 40’s and early 50’s, menopause is beginning or is well underway. At this time, the levels of estrogen and progesterone begin to fluctuate, with levels of estrogen dramatically decreasing. This leads to many of the symptoms commonly associated with menopause. With this reduction in the stimulation by estrogen to all tissues of the body, including the breast tissue, there is a reduction in the glandular tissue of the breasts. Without estrogen, the connective tissue of the breast becomes dehydrated and inelastic, and the breast tissue, which was prepared to make milk, shrinks and loses shape. This leads to the "sagging" of the breasts often associated with women of this age.

As a women matures into her late 40's and early 50's the levels of progesterone and estrogen begin to fluctuate. The decreasing levels of estrogen results in a significant decrease in the glandular tissue in the breast. The connective tissue begins to lose its elasticity and the breast
succumb to the effects of gravity.