ELI5: How is there always a seemingly ready and plentiful supply of sperm

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Because men make several million sperm cells per day, and there are always sperm cells in various stages of production. It’s not like after an ejaculation you need 2 months to make more. Today, you (if you’re male) will finish making, let’s say 30 million sperm cells. There are also 30 million more sperm cells at “99%” that will be ready tomorrow, 30 million more at 98% that will be ready the following day…etc. You also have a bunch of surplus sperm cells ,so you have multiple rounds in the chamber, so to speak. Also, it’s important to note that sperm is not the same is semen, sperm is a component of semen. Semen is almost entirely fluids from your seminal vesicles and prostate gland. An ejaculation with 50 million sperm cells is identical to one without except under a microscope. That’s why men who have had vasectomies or men who are infertile can still ejaculate. Fun extra fact: The reason testicles are external and not inside the body is because the ideal temperature for sperm production is a few degrees cooler than our core body temperature. Keeping the testicles in an external sac keeps them cooler for optimal sperm production. That’s also why the scrotum can tighten and sag. If it’s too cold, your scrotum will contract to bring your testicles closer to your body to keep them warm. Too warm, and it’ll relax and let them hang low away from your excess body heat.


Only about 2% of ejaculate are sperm. Most is nutritive fluid for their journey and produced by the prostate.


In your testes, you have things called seminferous tubules (which is a fancy way of saying sperm factories). They are filled with cells which can produce sperm cells- so many that you are able to produce around 1,500 per second! After they are produced they stay in a place called the epididymis which is where they stay and mature, into cells with motility, meaning they can swim to the egg and fertilise it when the time comes. As you said this process can take a while, usually between 60-75 days. Thankfully, sperm cells are super small (tens of millions in a millilitre of semen). So there is plenty of room for them to stay there and mature while more are being constantly produced. However, someone who masturbates multiple times a day will start to use up some of this supply – the volume of semen might (but not always) stay the same but the concentration of sperm cells in the liquid may decrease to help maintain a reserve. This is why fertility doctors may recommend you do not masturbate between attempts at trying for a baby. The numbers might not seem like they add up but remember concentration of sperm cells in the semen can decrease, while the same amount of semen roughly could be released several times a day, each time only releasing part of a reserve that has been there maturing for a while. Hope that helps


Also would like to add most of what you see when you ejaculate isn’t sperm but a cocktail of various fluids created by the prostate and other glands that help keep sperm mobile and alive while in the vagina. This is especially true if it’s your 2nd or 3rd time ejaculateing within 24 to 48 hours


So. Is there a limit of sperm that can be stored and how much is the max generally and also does the making of them stop when full?