Chestnut-shaped male reproductive organ, located under the bladder, which adds secretions to the sperm during ejaculation of semen .
It surrounds the urethra (see urinary system ) and is rounded at the top, narrowing to a blunt point. The prostate consists of 30–50 connective tissue , that discharge fluids into the urethra and two ejaculatory ducts. Those ducts, which also carry sperm and fluid discharged by the seminal vesicles, join the urethra inside the prostate. The prostate contributes 15–30% of the seminal fluid. It reaches its mature size at puberty . Around age 50, it commonly shrinks and decreases its secretions; an increase in size after midlife may be due to inflammation or malignancy. See also prostatic disorder .