Every time someone ejaculates, it produces millions of sperm. But the average pair of testicles produces billions of sperm cells over an entire lifetime. Answer: Because testicles have a complicated process to avoid running out of sperm and endangering future fertility. Sperm cells are derived from stem cells, that are tucked deep inside the testes. When these stem cells divide, they have a choice: They can become another pair of stem cells that will remain inside the testes. Or they can become a pair of more specialized cells, that start down the road to becoming sperm.
Semen , also known as seminal fluid , is an organic fluid that may contain spermatozoa. It is secreted by the gonads sexual glands and other sexual organs of male or hermaphroditic animals and can fertilize female ova. In humans, seminal fluid contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa, and provide a medium through which they can move or "swim". Semen is produced and originates from the seminal vesicle , which is located in the pelvis. The process that results in the discharge of semen is called ejaculation. Semen is also a form of genetic material. In animals, semen has been collected for cryoconservation.
BuzzFeed Science had the opportunity to chat about semen with Dr. It turns out semen is pretty freaking baller, and we have the facts to prove it. Spermatazoa, or sperm, is the name given to the reproductive cell that looks like a tadpole. Seminal fluid is the stuff that the tadpole swims in. Together they form semen — an armored tank carrying a fertilization superhero.
Since the late s, scientists have explored how to produce sperm where all of the chromosomes come from a female donor. Creating female sperm was first raised as a possibility in a patent filed in  by injecting a woman's cells into a man's testicles, though the patent focused mostly on injecting altered male cells into a man's testes to correct genetic diseases. In , Japanese scientists partially confirmed such techniques by creating chicken female sperm in a similar manner.