Breast (cont.)

1. Breast Cancer Slideshow
2. Take the Breast Cancer Quiz
3. Breast Cancer Screening

Although the primary biologic function of the breast is to produce milk to feed a baby, the breast has for many centuries been a symbol of femininity and beauty.

Despite the contemporary concept of an ideal breast, there is no single model that is ideal. The appearance of the normal female breast differs greatly from one woman to another woman, and the breast of any given woman even differs at different times during the woman's life -- before, during and after adolescence, during pregnancy, during the menstrual cycle, and after menopause.

Breast tissue begins to originate by the fourth week of fetal life. It grows along two ridges, one on either side, running from the armpit (axilla) to the groin. These are the so-called milk ridges or milk lines. Breast tissue can develop anywhere along the milk line. It is quite common to have breast tissue up toward and even in the armpit. An extra nipple (supernumerary nipple) can also develop anywhere along the milk line in both women and men, as can a complete auxiliary breast.

Picture of the milk lines

Rarely, the breast may be absent. The normal growth of the breast or nipple never takes place and there is no sign whatsoever of the breast tissue, areola or nipple.

Absence of the breast (also called amastia) frequently does not occur as the only physical problem. Unilateral amastia (amastia just on one side) is often associated with absence of the pectoral muscles (the muscles of the front of the chest). Bilateral amastia (with absence of both breasts) is associated in 40% of cases with multiple congenital anomalies (birth defects) involving other parts of the body as well.

Amastia can be distinguished from amazia -- wherein breast tissue is absent, but the nipple is present -- a condition that typically is a result of radiation or surgery.

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