Table of Contents
What is Ejaculation and Definition
The forceful contractions that expel SEMEN from the erect PENIS during the male ORGASM. Though ejaculation occurs as a result of sexual stimulation, the muscular contractions that produce ejaculation are not within voluntary control. Ejaculation moves semen (SPERM and seminal fluid) from the seminal vesicles, VAS DEFERENS, and PROSTATE GLAND into the URETHRA, and then ejects it from the urethra. In a man who has had a VASECTOMY, the semen does not contain sperm. A tiny valve at the urethral entrance to the BLADDER closes across the bladder opening, directing the flow of semen through the urethra to the outside of the penis. In a man who has had a PROSTATECTOMY (surgery to remove the prostate gland), ejaculation is retrograde (the semen enters the bladder instead of exiting through the urethra) because the OPERATION also involves removal of this valve.
For further discussion of ejaculation within the context of the structures and functions of reproduction and sexuality, please see the overview section “The Reproductive System.”
See also RETROGRADE EJACULATION.