Breast
From Encyclopædia
Breasts, in human females, are two glandular
organs that secrete
milk for feeding newborn infants. Such GLANDS are present in all
mammalS and are known in general as mammaries. Physiologically, they are highly modified sweat glands, but their precise evolution is not known. No other animals possess such glands, and no related precedents exist in other classes of vertebrates.Rudimentary breasts are present in both human sexes at birth. No further development takes place in males during normal
growth, but full development occurs in females during the early childbearing period. A projection called a nipple is found at the tip of each breast in both men and women. It is surrounded by a pigmented area, the areola, that is about 3.75 cm (1.5 in) in diameter and that enlarges and deepens in
color in pregnancy (see
PREGNANCY AND BIRTH).StructureThe female human breast consists mainly of a round
Mass of glandular tissue comprising about 15-20 lobes, each having a duct leading to an opening on the nipple; the duct system and glandular tissue fully develop with pregnancy. The amount of fat sheathing the glandular tissue determines the size of the breast. In a well-developed, well-nourished woman who has not borne a child, the breasts extend from the second or third rib to the sixth or seventh rib, and from the outer border of the breastbone (sternum) to the folds of the armpit. Connective tissues, or stroma, form the foundation or framework of the breast. The layer of ligaments directly beneath the breast sends strands into the breast itself, providing the firm consistency of the
organ. The deep layer of connective tissue sends strands in the opposite direction into the covering of the chest muscles; the connection is a loose one, enabling the breast to move freely over the chest wall.ExaminationBreast CANCER is an important medical problem, with women of age 35 or older at increasing risk of developing some form of the disease. Physicians urge that women conduct monthly self-examinations of their breasts to detect potentially cancerous lumps, because the disease is more curable when found at an early
stage. Another screening method is the X-ray process called MAMMOGRAPHY. Medical groups agree on the desirability of yearly mammography tests for women of 50 and older. Some groups also advise an initial test for women between 35 and 40, and a test every one or two years for women between 40 and 50, but other groups argue that the medical gains for the population at large do not justify the costs of such procedures. The alternative screening process called thermography has been characterized as a waste of time by the American College of
radiology. Other techniques for screening are also being explored.For many years, the most common approach taken in the treatment of breast cancer was MASTECTOMY--the removal of the breast and sometimes of surrounding tissues and muscles as well--along with X-ray treatments. Many physicians instead urge less dramatic lumpectomies, in combination with
radiation therapy and chemotherapy, but the subject remains one of considerable controversy.
bibliography: Day, N. E., and Miller, A. B., eds., Screening for Breast Cancer (1987); Dewar, Deborah, Breast Cancer: A Woman's Handbook (1983); Haagensen, Cushman, The Breast: Everything a Woman Needs to Know (1984) and Diseases of the Breast, 3d ed. (1986); Halbert, D. S., Your Breast and You (1986); Kopans, Daniel B., Breast Imaging (1988); Levy, Jerome, F., Your Breasts (1990); Lippman, M. E., et al., Diagnosis and Management of Breast Cancer (1987); Love, M., Dr. Susan Love's Breast Book (1990); Nama, P. G., et al., Breast Self-Examination and You (1987); Page, David L., and Anderson, Thomas J., Diagnostic Histopathology of the Br?ast (1988).
