The breast is the upper ventral region of the torso of a primate, in left and right sides, which in a female contains the mammary gland that secretes milk used to feed infants.
Both men and women develop breasts from the same embryological tissues. However, at puberty, female sex hormones, mainly estrogen, promote breast development, which does not occur in men, due to the higher amount of testosterone. As a result, women's breasts become far more prominent than those of men.
During pregnancy, the breast is responsive to a complex interplay of hormones that cause tissue development and enlargement in order to produce milk. Three such hormones are estrogen, progesterone and prolactin, which cause glandular tissue in the breast and the uterus to change during the menstrual cycle.
Each breast contains 15–20 lobes. The subcutaneous adipose tissue covering the lobes gives the breast its size and shape. Each lobe is composed of many lobules, at the end of which are sacs where milk is produced in response to hormonal signals.
Read more about Breast: Etymology, Development
Famous quotes containing the word breast:
“It is time that beats in the breast and it is time
That batters against the mind, silent and proud,
The mind that knows it is destroyed by time.”
—Wallace Stevens (1879–1955)
“His breast was the seat of all those passions which degrade our nature, and disturb our reason. There they raged in a perpetual conflict; but avarice, the meanest of them all, generally triumphed, ruled absolutely, and in many instances, which I forbear to mention, most scandalously.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“Getting ready: the show girl scratches her breast and shakes out her feathers.”
—Mason Cooley (b. 1927)