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Breast
(Anatomy and Function)

Facts on the Breast

  • The breast generally refers to the front of the chest and medically specifically to the mammary gland.
  • (The word "mammary" comes from "mamma," the Greek and Latin word for the breast, which derives from the cry "mama" uttered by infants and young children, sometimes meaning "I want to feed at the breast.")

Mammary Gland Design

  • The mammary gland is a milk-producing structure that is composed largely of fat cells (cells capable of storing fat). The fat deposits are laid down in the breast under the influence of the female hormone estrogen.
  • Just as the surge of estrogens at adolescence encourages this process, androgens, such as testosterone, discourage it.
  • Within the mammary gland there is a complex network of branching ducts (tubes or channels). These ducts exit from sac-like structures called lobules.
  • The lobules in the breast are the glands that can produce milk in females when they receive the appropriate hormonal stimulation.
  • The breast ducts transport milk from the lobules out to the nipple. The milk exits the ducts from the breast at the nipple.

Picture of the anatomy of the breast
Picture of the anatomy of the breast

Human Breasts Differ from Other Primates Breasts

Human breasts function somewhat differently than those of other primates. In other primates, the breasts grow only when the female is producing milk (lactating). When the non-human primate female has weaned her young, her breasts flatten back down. In humans, the breasts develop at adolescence usually well before any pregnancy has occurred and the breasts stay enlarged throughout the remainder of life.

Breast Changes During Pregnancy

Patient Comments

During pregnancy the breasts grow further. This growth is much more uniform than that at adolescence. The breasts of women with small breasts tend to grow about as much during pregnancy as those of women with large breasts. The amount of milk-producing tissue is essentially the same. This is the reason that when milk production begins, small-breasted women produce as much milk as do large-breasted women.

Medically Reviewed by a Doctor on 9/28/2016

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