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:
“When the cross blue lightning seemed to open
The breast of heaven, I did present myself
Even in the aim and very flash of it.”
—William Shakespeare (1564–1616)
“Laughter and grief join hands. Always the heart
Clumps in the breast with heavy stride;
The face grows lined and wrinkled like a chart,
The eyes bloodshot with tears and tide.
Let the wind blow, for many a man shall die.”
—Karl Shapiro (b. 1913)