Breast development is a complex
biological process in
primates that takes place throughout a
female's life. It occurs across several phases, including
prenatal development,
puberty, and
pregnancy. At
menopause, breast development ceases and the breasts atrophy. Breast development results in prominent and developed structures on the chest known as
breasts in primates, which serve as both a
sexual characteristic and as
mammary glands. The process is mediated by an assortment of
hormones and
growth factors, the most important of which include
estrogen,
progesterone,
prolactin,
growth hormone, and
insulin-like growth factor 1.