Production of semen

Semen is a fluid that contains sperm cells and is produced and released by the man’s sexual organs. Semen is produced like this:

• The testicles (balls) produce millions of sperm cells.
• The sperm cells ripen and are stored in the epididymides.
• When a man has an ejaculation, the sperm cells are pushed through the sperm ducts.
• The sperm cells are transported to the prostate and seminal vesicles. Fluid is added to the sperm cells. Together the fluid and the sperm cells make up the semen.
• The semen is pushed out of the penis through the urethra.

A man produces semen for the first time during puberty. In general, a boy becomes fertile between the ages of 12 and 15. He can then have children even if he is having sexual intercourse for the first time.
The man produces sperm cells his entire life. Most men can have children all their lives.

A woman can only get pregnant if sperm cells enter her uterus via her vagina during her fertile days.
Before he ejaculates, a man may already lose a bit of fluid that might contain sperm cells (pre-ejaculate). Withdrawing the penis before ejaculation is not a safe method of contraception.
A man who has undergone sterilization produces semen without sperm cells. He can have sexual intercourse and ejaculate normally without fear of making a woman pregnant.