Semen is a sperm carrier produced in the male reproductive system. The sperm takes almost three months to mature, and they have short lifespans outside of the male body. Those sperm that make their way into the female reproductive system last longer than those that do not.
The typical semen lifespan begins in the male testes. This process starts at puberty and creates about 1,500 sperm a second from then on. Semen is the entire product of the male reproductive system, and it includes both the cells that fertilize the female egg, which are sperm, and the fluid that carries the sperm, known as seminal fluid. From the beginning of the semen lifespan in the testes, the sperm move through to tubes called the epidymidis, where they develop the ability to move around. At the point of an orgasm, the male body then moves the sperm through the body, collecting seminal fluid on the way out and on to the outside of the body.
Inside the body, the sperm can live for as long as 72 days. When they leave the body, the semen lifespan depends on their environment. In situations where sperm are not ejaculated into a female, they tend to have shorter lifespans. A few minutes to several hours is the typical semen lifespan of these sperm.
When the sperm find their way inside a female, however, not all of them make it past the acidic environment of the vagina. This inhospitable environment plays a role in protecting the vagina against infectious disease, and many sperm die there, even though the seminal fluid helps protect the sperm from harm. The majority of the sperm die before reaching the Fallopian tubes, where fertilization can occur. From an initial presence of as many as 300 million sperm in the ejaculate, only about 200 individuals are left to compete during the fertilization process.
Sperm that make it past the cervix, which is the entrance to the uterus, can get to the uterus in as little as 10 minutes after intercourse. More semen at the cervix can take as long as three days to move up into the uterus. Overall, semen in the female body can survive for five days after insertion and cause fertilization of eggs during that time. From the time that a single sperm manages to reach an egg and fuse with it until the egg starts dividing into an embryo, only 24 hours will pass.