Ventral view, pelvic region

The prostate gland is an accessory sex gland, which releases its secretions into the urethra during ejaculation, thereby contributing to the makeup of the semen.  The prostate secretion makes up about one-third of the volume of the semen.  The prostate secretion includes materials that aid in motility of the spermatozoa.  The prostate is the enlarged area at the tip of the probe.  It surrounds the urethra.