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:
“He fancied that I gave a soul
Did but our bodies touch,
And laughed upon his breast to think
Beast gave beast as much.”
—William Butler Yeats (1865–1939)
“The forehead and the little ears
Have gone where Saturn keeps the years;
The breast where roses could not live
Has done with rising and with falling.”
—Edwin Arlington Robinson (1869–1935)
“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)