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Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is 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.")

How is the mammary gland designed?

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 ducts exit from the breast at the nipple.

How are human breasts different from those of other primates?

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.