Note:  Do not rely on this information. It is very old.


Breast, or mammary gland, is the organ concerned in secreting milk. The gland substance proper is surrounded by connective tissue and fat, Which forms a kind of packing and supporting material. The gland itself is made up of a number of lobes, each lobe being further divided into lobules. These lobules are found on microscopical examination to be composed of a number of acini or hollow sacs lined by cubical epithelial cells which all open into a common duct. By the union of such lobular ducts, the main ducts of the gland, the lactiferous or galactophorous ducts, are formed; these are about fifteen in number and, radiating towards the nipple, open by separate orifices upon it. Just before reaching the surface each main duct presents a dilatation, a sort of reservoir for the accumulation of the secretion. The nipple contains in addition to these terminations of the ducts a supporting framework of areolar tissue, unstriped muscle fibres, and numerous blood-vessels. It is surrounded by an areola of pink or brownish skin. In the female at the time of puberty the breasts enlarge; during pregnancy further development occurs, and culminates ultimately in profuse secretion of milk after childbirth.