Mara Steinkamp, Graduate Student, Human Genetics and Diane Robins, Ph.D., Professor, Department of Human Genetics, University of Michigan Medical School

The mouse mammary gland is a highly specialized tissue consisting of milk-producing alveolar cells and a network of ducts that transport the milk to the nipple. Beginning at puberty, ducts grow out from the nipple, invading the surrounding fat pad. Many of the factors important in the development of the mammary gland may also be involved in breast cancer initiation and in subsequent tumor growth.  This picture shows the mature duct tree of a non-pregnant mouse. Because the ducts are composed of tightly packed cells, they appear darkly stained (here, blue/brown) while the surrounding fat pad (here in tan) remains unstained.