Sperm is the male reproductive cell or gamete, which carry half the genetic material for a person’s offspring. The egg carries the other half; when combined, during fertilization, they make a unique genetic sequence. Sperm cells are produced in the seminiferous tubules of the testes in a process known as spermatogenesis.

What is sperm?

Sperm are reproductive cells produced by the biological male humans and animals. Sperm contain half of the genetic material (DNA) for the future baby. Sperm combines with an egg in a process called fertilization which can result in pregnancy.

Each milliliter of semen contains, on average, around 80 million sperm.

A sperm’s anatomy includes:

  • the acrosome, the tip of the head that helps the sperm penetrate an egg
  • the head, which contains DNA
  • the midpiece, which contains mitochondria for energy
  • the tail, which moves back and forth to help the sperm progress through the female reproductive tract to the egg

How sperm is produced

Sperm is made in the seminiferous tubules in the testicles. This process, called spermatogenesis, next moves the sperm through the epididymis, where sperm mature and gain motility. Finally, sperm are stored in the tail of the epididymis until they’re ejaculated from the body.

The whole process of spermatogenesis takes around 64–72 days, but sperm are being produced constantly. Over 100 million sperm can be produced each day.

Sperm and fertility

Sperm are key for fertility since they contain the genetic material that, when combined with the DNA in an egg, becomes a baby. To conceive a child, it’s helpful to have healthy sperm. This involves:

Even if sperm show abnormalities, they may still be capable of fertilizing an egg.

History of sperm

Sperm cells were discovered in 1677, followed by more detailed observations of the male reproductive system in the 1800s. The egg was discovered in 1827, helping further the understanding of fertilization.

By the 1930s, semen analysis was used to assess infertility. Cryopreservation and successful pregnancies using frozen sperm occurred over the next few decades. In 1980, the World Health Organization first published a range of normal values for semen, providing a reference for evaluating sperm health and fertility.

Back to Glossary