Prostate cancer. Coloured scanning electron micrograph (SEM) of tissue from the prostate gland of a patient suffering from prostate cancer. Cancer cells (purple/pink) within an acinus, a secretory duct, are seen here. Malignant cells divide rapidly and chaotically, and can clump to form tumours which invade and destroy surrounding tissues. The prostate gland is a part of the male reproductive system located below the bladder. Prostate cancer can cause difficulty in passing urine and an increased need to urinate. Magnification unknown.