The composition of the breast includes skin, adipose tissue, mammary glands and the fibrous connective tissue therein. The mammary glands have the function of lactation and are the main functional structures. Generally, the mammary gland is divided into 15-20 lobes by connective tissue, and each lobe has a milk duct. The ducts are located close to the nipple, and their ends taper and open into the nipple. The lobes and ducts are arranged radially around the nipple. The fascia of the chest wall forms the envelope of the mammary gland and sends out bundles of fibers that connect with the pectoral muscle fascia and skin to support and anchor the breast. The breasts of the average adult nonpregnant woman are hemispherical. Their size and shape vary greatly, mainly based on the amount of fibrous and fatty tissue they contain. Their lactation function is mainly regulated by hormones in the body.