Ductal breast cancer. Transmission electron micrograph (TEM) of a section through breast tissue, showing malignant (cancerous) epithelial cells arising from the milk ducts of the breast. Cell nuclei, which contain the cell’s genetic information, are dark blue. Cancers originating from ducts are known as ductal carcinomas. Breast cancer is the most common type of cancer in women, and most breast cancers are ductal. The cancer can invade surrounding tissue and spread to other parts of the body (metastasis). Magnification: x2500, when printed 10 centimetres wide.