THE MAMMARY GLAND is a dynamic organ, capable of extensive growth, regeneration, and remodeling. The growth demands placed on the mammary gland during embryonic development and throughout adulthood, suggests a function for mammary stem/progenitor cells. Indeed, functional testing of mammary stem cell activity in rodent models has revealed the presence of sub—populations of cells with the ability to recapitulate adult mammary gland development. As yet, there are no markers known that are specifically expressed only by stem cells that can reveal their activation or distribution. Although the contribution of mammary stem cells to breast cancer has yet to be determined, it has been proposed that these cells may play a significant role in mammary tumorigenesis.

Mammary glands are secretory organs derived from the epidermis, which are ...