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What is the difference between sperm and semen?

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Front view anatomical diagrams of the male and female reproductive systems, with labeled organs including penis, testis, prostate gland, uterus, ovary, and vagina. — human reproductive system Organs and structures of the male and female reproductive systems.

The terms sperm and semen are often used interchangeably, but they refer to distinct components of the male reproductive system.

Sperm are the male reproductive cells produced in the testes. These cells are responsible for fertilization and carry the genetic material necessary to create offspring. Each sperm cell consists of a head, which contains the nucleus and chromosomes, and a tail (flagellum) that provides motility.12

Semen is the complete fluid emitted from the male reproductive tract during ejaculation. Sperm cells actually constitute only a small fraction—typically about 1 to 5 percent—of the total volume of semen. The remainder of the fluid, known as seminal plasma, is composed of secretions from various accessory glands, including the seminal vesicles, prostate gland, and bulbourethral glands. This fluid provides essential nutrients, such as fructose, and creates an alkaline environment that protects the sperm and facilitates their survival and movement toward the egg.134