Take everything you know about semen and throw it out the window, because you were lied to. Yes it comes out of the penis during ejaculation, but beyond that you are probably filled with misconceptions; just like semen is filled with much more than just sperm. If you really want to learn all the weird facts about semen and be smarter than your friends, you need to watch this video. There is most definitely sperm in semen, but not as much as you might think. Also, this is where we’ll break one of the most common misconceptions. Semen and sperm are not the same thing. Sperm is the male sex cell that is produced in the testes and carries half of the DNA to make a baby. Semen on the other hand is a mixture of lots of different proteins, lipids, fluids, and sperm. With each fact about this mysterious substance things are going to get weirder and weirder. One of the most common questions about semen has to do with what is called pre-ejaculate or pre-cum. Is the liquid that comes out of the penis before ejaculation semen? And whatever it is, can it get a female pregnant? We have these answers, but first we need to understand what semen actually consists of. Most of the semen isn’t created in the testicles. Instead, the substance is made in three different areas of the male body, and are mixed together just as a man ejaculates. During orgasm the sperm travels through the seminal vesicles where a yellowish fluid rich in fructose is produced and mixed in with the sperm. This is what around 70% of the semen is actually made of. After the seminal vesicles the concoction passes through the prostate where a fluid containing enzymes, citric acid, phosphates, and lipids is added. Lastly, just before ejaculation, the fluid goes through the bulbourethral glands which secretes lubrication to allow the sperm to pass out of the urethra. Who knew the journey of semen was full of so many twists and turns? When the semen comes out of the penis it is almost entirely made up of proteins and water. Only 1 to 5% of the semen is actually sperm. Granted, in the average teaspoon size ejaculation of semen there are around 200 to 500 million sperm cells. However, the vast majority of the substance is not sperm. You may be asking yourself: “why do men create so much other stuff while ejaculating?” The answer is pretty crazy, and has to do with how hostile the vagina is. For sperm the female reproductive system is a difficult and treacherous path to navigate. In order for the sperm to even stand the slightest chance of reaching an egg, it needs to be contained within the protective liquids of semen. The vagina itself is too acidic for sperm to survive in. Also, the female’s immune cells patrol the reproductive system, and they will identify and destroy sperm on sight if it is not contained within the semen. The contents of seminal fluid, which is just a fancy way of saying semen, creates a safe barrier between the sperm and everything that wants to kill it in the female’s body. We are now back to the question: what is pre-ejaculate and can it get a female pregnant? It is actually not semen at all. Instead the pre-ejaculate is secreted by the Cowper’s gland, which is not used in the production of semen or sperm. It is thought that this liquid is used to help lubricate the tip of the penis to allow for easier penetration during sex. Therefore, pre-ejaculate can not get a female pregnant. That being said, if a male has recently ejaculated and some sperm was able to survive in the urethra, the pre-ejaculate could flush some of that sperm into the vagina if a couple goes for round two immediately after climax was achieved by the male. To be extra careful, and make sure that the lubricant doesn’t contain any sperm, flush the system by peeing before going at it again. Or use a condom. Or get a vasectomy. Any of these things are viable options. Now that we’re all on the same page about semen let’s get into some even more bizarre facts about the ejaculate. Semen doesn't just protect the sperm from the female’s body, but from the body it came from as well. The testicles are considered an "immunologically privileged site." This means they are protected from the body’s own immune system so the sperm inside of them is not destroyed. Since the male doesn’t produce sperm until after puberty, the already developed immune system doesn’t recognize sperm cells as part of it’s own body. Therefore, once sperm leaves the safety of the testicles the immune cells can immediately try to destroy them. The semen that the sperm is contained in protects the sex cells and allows them to quickly move out of the male’s body during ejaculation before they are destroyed. And if that isn’t crazy enough, think about what semen allows sperm to do once it leaves the body. Sperm is the only human cell that is produced in one person, but meant to survive inside another. This is how people get pregnant. Without the semen, sperm would not be able to survive long enough inside a female body to complete their mission. The sperm are explorers, and the semen is their spaceship to travel to the final frontier. Now let’s get into some of the other weird facts about sperm that you may be wondering about. One of the most surprising things about semen actually has to do with a surgery. Men get vasectomies for different reasons. Maybe they aren’t ready for children, and want to have sex with less risk of getting their partner pregnant. Regardless of the reasoning, a vasectomy operation is done by separating the tubes called the vas deferens that transport sperm from the testes to the urethra. By snipping this tube sperm is not able to leave the male body. However, that is not the case for the man’s semen. When you think of a vasectomy you might assume that the male will no longer ejaculate at all, but this is not true. Males who undergo this operation still ejaculate about the same amount of semen as before, there just isn’t any sperm in it. The only part that is missing in the semen from a man with a vasectomy is the 1 to 5% of the sperm that normally mixes in with the other fluids. Something else to note is that a vasectomy will not prevent the spread of STDs, which are still transferred in the fluids swapped during sex, whether it be vaginal, anal, or oral. For men who still have their vas deferens attached to the rest of the reproductive system there is another weird fact about the sperm mixed in with their semen. Only about half the sperm are functional. So really when a man ejaculates the amount of healthy sperm in the semen is closer to 1%. The sperm that are not viable tend to be misshapen. They can have two heads or two tails. The sperm could be too big or too small. Really it’s a miracle that males can get the job done at all sometimes. And sticking with testicles, do you need two in order to produce enough semen for pregnancy? The answer is one testicle will do just fine. Even if a male only has one testicle he can still produce enough sperm and semen to impregnate a female. Interestingly, if a man loses a testicle sometimes the remaining one will grow slightly to produce more sperm. Even if the mixture of sperm in the semen is cut in half, there are still hundreds of millions of sperm in the fluid, which is definitely enough to cause pregnancy. It just means that the couple may need to have more sex. Which could be good news to hear. Our last weird fact about semen is that the size of the load does not correlate to fertility. A large ejaculation with lots of semen, or a smaller one, contain about the same amount of sperm. It is only the amount of liquids and other parts of the semen that increases. The average ejaculation amount is around a teaspoon of semen. Whether a man’s ejaculation is more than that, or slightly less, it will still contain hundreds of millions of sperm. So, in terms of the amount of semen in an ejaculation, size doesn’t matter. Now watch “Weird Facts About Testicles.” Or check out “Weird Facts about Male Body.”