Light micrograph of a test for prostate cancer using Prostate Specific Antigen (PSA) antibody labeling. Dye is injected into the prostate gland, and binds to proteins altered by prostate cancer cells to form PSA. Here, the dye has bonded to cancerous epithelial cells (red) of the glandular follicles. Healthy glandular tissue surrounds the cancer (purple). The prostate gland is a part of the male reproductive system. It is located under the bladder and secretes seminal fluid. Prostate cancer is a common cancer in men. Symptoms include increased need to urinate. Treatment includes surgery and radiotherapy. LM 10x at 35mm.