The main function of the prostate is to supply fluid for sperm that has been collected in the seminal vesicles .
Ejaculation is when the seminal vesicles and prostate empty.
The seminal vesicles are supplied by the vas deferens from the epididymis , a tightly coiled, tube next to the testicle that provides for the storage, transmission, and maturation of sperm. Before ejaculation, the Cowper's glands secrete an alkaline fluid that neutralizes any urine that may be left in the urethra. The fluid also has a lubricating quality. Because these glands are often spared in a prostatectomy, they may continue to function, even though there is no ejaculate. The position of the prostate allows a digital rectal examination or DRE to obtain information about the prostate.