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Breast Development |
 Two breasts are never identical
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At puberty, the female breast develops, under the influence of estrogen,
progesterone, growth hormone, prolactin, insulin and probably thyroid
hormone, parathyroid hormone and cortisol. This complex process
typically begins between ages 8 to 14 and spans about 4 years.
The breast contains mostly fat tissue, connective tissue, and glands that following pregnancy, will produce milk. The milk is collected in the ducts and transported to 15-25 openings through the nipple.
During the menstrual cycle, the breast is smallest on days 4-7, and then begins to enlarge, under the influence of estrogen and later progesterone and prolactin.
Maximum breast size occurs just prior to the onset of menses.
The breast is not round, but has a "tail" of breast tissue extending up into the axilla (or armpit).
This is clinically significant because abnormalities can arise there just as they can in other areas of the breast. During breast examinations, this area should be palpated.
Breasts are never identical, comparing right to left. One is invariably a little larger, slightly different in shape, and location on the chest wall. The nipples are likewise never identical but show minor differences in size, location and orientation.
The breast is divided into quadrants to better describe and compare clinical findings.
The upper outer quadrant is the area of greatest mass of breast tissue. It is also the area in which about half of all breast cancers will develop.