ABSTRACT
BREAST DEVELOPMENT The female breast undergoes dramatic changes in size, shape and function during growth, puberty, pregnancy, lactation, and postmenopausal regression. Lobular formation occurs at puberty but the completion of breast development and cellular differentiation occurs only at the end of a full-term pregnancy. With pregnancy, the mammary parenchyma reaches its final stages of development with secretory lobules. It is postulated that the induction of cellular differentiation of the breast by pregnancy is partially responsible for the inhibition of carcinogenic initiation.
