Science Questions

What happens to sperm that isn't ejaculated?

What happens to all the sperm that isn’t ejaculated, where does it go and is it still healthy? Natasha

Chris -   Yes.  It’s a very good question because obviously the testes make sperm. They make sperm at about 5000 sperm a second at peak. So they can make sperm at prodigiously fast rates. And they put that sperm into what are called the seminal vesicles, which are structures up inside the body. So sperm are made at a lower temperature, the testicles. That’s why they’re outside the body because the temperature is about one degree lower. But then the sperm are best stored and kept viable inside the body of body temperature 37 degrees.  So they’re going to these seminal vesicles.  They’re nourished there.  They have various components of semen which has got fructose and other sugars and things, and it’s to keep the sperm healthy.

They can survive for quite a long period of time inside the body but eventually they will fatigue and they will age. And of course all the things that you take into your body, cigarette smoke, other toxins and things will damage the sperm potentially.  So they have a sort of recycle time. So sperm that have reached their sell-by-dates get scavenged back and broken down in the same way that, let’s say, blood cells get broken down. And basically any of the nutrients and goodies in the sperm just get recycled back inside the body, and new sperm are produced to make up for the shortage.

Helen: -   So it’s a kind of continual, sort of, replacement, really. 

Chris: -   Exactly.  Those that don’t leave the body eventually break down, and are scavenged back.

November 2009