Breast Cancer Breast Cancer Return to the tutorial menu. The female breasts are modified sweat glands composed of lobes and lobules interspersed with adipose tissue and connective tissue.
Ducts drain from each lobule.
These converge to form a lactiferous duct that drains from each lobe. The lactiferous ducts merge just beneath the nipple to form a lactiferous sinus. The functional secretory unit in lactation is the terminal duct lobular unit. Here, each duct has a lining epithelium surrounded by a thin myoepithelial cell layer responsive to oxytocin, the hormone that stimulates lactation. Neoplasms may arise in either the ductular epithelium, lobules, or the stroma.