Prostate cancer cell. Coloured scanning electron (SEM) micrograph of a moving prostate cancer cell on a filter (green). The cell spreads through thin cytoplasmic extensions called filopodia. The prostate is a small gland found in men just below the bladder surrounding the urethra, the tube urine passes through. Prostate cancer is most prevalent in men over 50 years of age. Magnification: x2150 when printed at 10 centimetres wide.