The breasts

Abstract

The female breasts which at birth consist almost wholly of a group of straight tubules of ectodermal origin, begin to develop at puberty when the ducts commence to branch, fat is deposited subcutaneously and fibrous tissue increases in amount. After puberty, ovarian oestrogens cause the ductal system to elongate and branch, and buds form in the distal part of the branches. These buds or clusters of cells are the potential breast alveoli and the formation and further development is induced by progesterone. Other hormones, too, are involved in breast development including thyroid and adrenal secretions, pituitary growth hormone (somatotrophin) and prolactin.