This is whole mount image taken directly off a microscopic slide. The blue nodules here are surrounded by clear zones in some areas, and in other areas there is pink, fibrous tissue present. This image shows the growth pattern of cancer cells confined to the ductal system. Like a cross section of many "soda straws," the blue areas represent ducts that contain tumor cells. Ductal carcinoma in situ means that malignant cells exist in the tubules, but haven't invaded beyond the tubules or ducts. The reason there are round, blue nodules is that tubules have been cut in cross section. Since there is no invasion, the spaces between the blue tubules are filled with fat or fibrous tissue. The black dots are placed around the periphery of this tumor for measurement purposes.