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The Testicles

A graphic image of testicles and the text 'My Amazing Body'
How much do you really know about how the testicles work?

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My Amazing Body is a podcast where we explore interesting, unknown and misunderstood parts of your body with help from medical experts and stories from real Queenslanders.

This episode is all about the testicles. We quiz Queenslanders to find out just how much the average person knows about the testicles. Dr Annie Roberts, paediatric surgery fellow at Queensland Children’s Hospital, explains how the testicles develop throughout childhood and adolescence, what role the testicles play in the body and how they work. She also speaks about the common conditions that can cause pain or disease in the testicles, and when boys and men need to see a doctor for testicular troubles.

Enjoyed this episode? Listen to episode 3, all about The Ovaries, to learn more about the human reproductive system.

Meet our guests

Our guest expert, Dr Annie Roberts, is a paediatric surgery fellow at Queensland Children’s Hospital.

A photo of Dr Annie Roberts wearing her surgical scrubs.

Episode materials

Audio is great, but some things are best seen as well as heard. These materials provide more information about topics we touch on in the show.

A diagram of the testicles

A diagram of the testicles.

Testicular torsion

At 12:20 Dr Roberts talks about the importance of boys and men heading straight to a hospital emergency department if they have testicular pain, in case they could have testicular torsion. Testicular torsion occurs when spermatic cord that the testicle is attached to gets twisted. This can cut off blood supply to testis and requires emergency surgery to fix. Not all pain in the testicles means torsion, but it’s really important that boys and men go straight to a hospital to get checked if they’re in pain. You can find more information about testicular torsion at the links below.

Teens Health: Testicular torsion

Children’s Health Queensland: Testicular torsion

Better Health Channel: Testicle injuries and conditions

Health Direct: Swollen or painful testicle

Testicular cancer

At 16:03, we discuss testicular cancer. Testicular cancer is the second most common cancer in young Australian men. Dr Roberts recommends boys men get familiar with the normal look and feel of their testicles, and let their GP know if they notice any changes. You can find more information about testicular cancer at the links below.

Cancer Council: Testicular cancer

Health Direct: Testicular cancer

Cancer Australia: What is testicular cancer?

Australian Urology Associates: Testicular cancer and self-examination

Movember: Know Thy Nuts

Episode transcript

Vox pop: Nuts.

Vox pop: Bollocks.

Vox pop: Junk.

Vox pop: Rocks? Cherries? The boys?

Vox pop: Goolies, um...knackers.

Vox pop: Man berries.

Vox pop: Nads!

Vox pop: Cajones, gonads, man berries...the list goes on and on!

Vox pop: Well I guess we all know them as the balls, and a million other words I guess. But, what are they?

Host: Hi, I'm Elise. Welcome to the latest episode My Amazing Body, where we explore interesting, unknown and misunderstood parts of your body. Today, we're learning all about the testicles.

How familiar are you with the testicles? Sure, you know it really hurts if they get hit, and you might kind of know what they do, but how much do you know about the specifics? We took to the streets to find out just how familiar Queenslanders are with the testicles.

Vox pop: Well I know I have them.

Vox pop: I don't get a good visual of them so, I couldn't give you a clear answer…

Host: We decided it was time for Queenslanders to get the lowdown on what's going on downtown for men and learn more about these key parts of the male anatomy. After all, we all came from them, right?

We spoke with Dr Annie Roberts, paediatric surgical fellow at Queensland Children's Hospital, about the testicles. We discovered how they're formed, how they work, and what boys and men need to know about looking after their testicles to keep them healthy and functioning properly.

Dr Roberts: I'm Annie Roberts, I'm one of the paediatric surgical fellows at Queensland Children's Hospital. I work with children and their families when they have a surgical problem that needs to be fixed, either in the short term or the long term. I look after them before, during and after their operation.

Host: As part of her job, Dr Roberts works with boys and young men who have concerns about their testicular health.

Dr Roberts: When a kid comes to my clinic, and I need to examine their testes I always say to them, “This is really normal to me.” I see somewhere between 10 and 15 of the same thing in the clinic every time I do a clinic. It’s really embarrassing for you because it's your body, but it’s really normal for me. And if they realized that they're normal, like if I say to a kid, “I've already seen two kids with testicular pain today”, that normalizes it for them. Doesn't make it much less scary because it’s an unknown, but it normalises it and makes say, everyone’s the same.

Host: Did you know that the word avocado comes from the Aztec word for testicle? It's easy to see the similarities, but most of us are more familiar with the inside of an avocado than we are with the inner workings of the testicles.

Vox pop: Probably a little bit bigger than marble size each.

Vox pop: So, I couldn't really give you a size. Are you looking for centimetres? Size of a ping pong ball is probably a bit too big? I don't know.

Vox pop: Geez, actually, I'm trying to think of fruit. Like a large grape.

Host: Dr Roberts explained exactly what the testicles are, and how they connect to the rest of the body.

Dr Roberts: So, the testicles are two egg-shaped structures that sit in the scrotum of a male. The testes are connected to the urogenital tract. And so, they sit in the scrotum and they attach by a cord and they sit as the vas and the vessels running up into the groin. The vas goes into the belly and connects to the prostate and the urethra, allowing sperm to come from the testes out to the outside world.

Host: Many men will find that they're testes aren't exactly symmetrical – one will might be bigger than the other or hang lower within the scrotum. Dr Roberts says that this is completely normal and doesn't impact on the testicles’ function at all.

Dr Roberts: If you look at the studies that have looked at testicular size, some find that one is slightly bigger than the other, but there's no consistency. Some find they're the same. And I think you need to think about it like your feet. Neither of your feet are exactly the same size, your hands aren't exactly the same size, your face is not perfectly symmetrical. And so, there's some variation anyway. Whether that's blood supply or a whole lot of different things, no one really knows.

Host: The testicles have two really important main jobs in the male body: making sperm and making testosterone.

Dr Roberts: Testosterone’s the main thing. There are some other cells in the testis that are support cells. So, the testis is made up of two different groups of cells; the stromal cells, which are the support cells, and within those stromal cells, there's some support cells for the tubes that make the sperm, and then there's some support cells that produce testosterone and they're called Leydig cells. The tubes that make the sperm are called seminiferous tubules, and they're about 70 centimetres long, all coiled up in really tight packages. And there's about 800 per testis.

Host: While boys' testicles start to produce functioning sperm during puberty, Dr Roberts says that the process of creating sperm starts when they're a baby.

Dr Roberts: There's a series of progressions that need to happen and the first bits start when they're a tiny baby. And that progress though…you don't form mature sperm that can become a baby until you're post-pubertal, that is you've gone through puberty. And in that early phase of puberty, the variation in how many normal sperm you're producing is huge.

And in that hormonal imbalance period where there's so much rapid change, and that's when boys, their voice is breaking and things. It's really interesting, if you look at ejaculates from boys that age in that teenage period, they can have one ejaculate that has no functional sperm, essentially, and one ejaculate that looks completely like an adult male. And there's so much variation in between. So, they're sort of still warming up and getting prepared. But it doesn't mean that they can't have babies at that point so they still need to practice safe sex and things, so that they don't end up with having a baby that's unexpected.

Host: A man's body is constantly making new sperm, and it turns out it's a very complicated process, that takes a lot longer than you might think.

Vox pop: I'd say minutes…

Vox pop: I thought it was like a day. Don't you pee them out?

Vox pop: Once somebody's ejaculated then they need to regenerate? I wouldn't know. I don't know. They'd need a bit of a rest. Could it be 5 minutes? Could it be 20 minutes? Could it be an hour? I think it'd only be a few minutes.

Vox pop: Not long, I reckon it would be a couple of hours. Maybe. Maybe. Not sure.

Host: What do you think? A few minutes, hours, days? Dr Roberts said that sperm creation is actually a process that takes weeks from start to finish.

Dr Roberts: That process is called spermatogenesis. And there are a series of stages of division of the cells and modifications that become more and more specialised so that it becomes a sperm as we know it, with a head and a tail. And the tail is then the thing that functionally causes the propulsion forward so that the sperm can meet the egg in the female reproductive tract.

The series of things that happen to get from the original cells right through a lot of those…a lot of people spend their entire life looking at it, it's quite complicated! But the basic thing is each of the cell stages there's multiple steps. And at each stage, something can go wrong, and that individual cell will then be discarded and absorbed by the body. And at each of those stages, you're getting more and more specialised, to actually finally make the sperm cell.

And that takes about 60-70 days. And then, after they've matured, they can be ejaculated. What's really interesting is that there's about 1,000 of those sperm being produced every second. So, it's a huge number being produced. Most of them clearly don't end up becoming anything, and they're just either absorbed by the body or ejaculated.

Host: If the testicles are such an important part of the body, it's worth asking why they sit on the outside, unprotected? It all comes down to climate control; the testicles, and the sperm they produce, are really sensitive to temperature. A man's body will be constantly monitoring and moving the testicles within the scrotum to ensure they're staying at the perfect temperature. When they're hanging outside in the scrotum, they can stay nice and cool. On a cold day, or in cold water, they might draw up towards the body to stay warm.

Dr Roberts: Yeah, two or three degrees cooler in the scrotum. It's such a significant temperature change, and it really impacts upon sperm development. We know in kids that have had undescended testes, so testes that didn't come down properly, if we do biopsies on them, their sperm development is different, just because of the temperature difference, we think.

Host: Are you ready for this episode's Mystery Body Part? See if you can guess the body part from the clues given. We'll reveal the answer at the end of the episode.

You have two of me, though some people have many extras. I can be inverted, or I can point outwards. I have my own sweat glands. I can be lots of different colours, including pink, red, brown and black, and might change colour over time or at different stages of life. Do you know what I am?

Some men describe receiving a blow to the testicles as the worst possible pain they can imagine.

Vox pop: Oh yeah; pain, suffering, keeling over, lying down for a very long period of time, needing to take a time out, tears.

Vox pop: Quite exquisitely, beautifully painful. It's a dull ache that kind of intensifies for about four seconds until it's excruciatingly painful and then takes about two and a half hours to go away.

Vox pop: A look of complete agony. Normally folding over in half, and just excruciating pain.

Host: Dr Roberts said that it's not known exactly why it hurts so much for a man to get hit in the testicles.

Dr Roberts: I have looked, and I can't find any papers that will tell you that. I presume it's because it's got so many nerves that supply that area, and I think it's interesting because the areas that need to be protected the most often have a high nerve supply to them.

Host: The nerves of the testicles are connected to one of the major nerves in the body, the vagus nerve, that runs all the way from the brain stem to the colon. This connection might account for the variety of bodily sensations a man feels after a blow to the testicles, from nausea in the guts to dizziness in the head.

Regardless of why it hurts, Dr Roberts says it's important for boys and men to protect their testicles from injury.

Dr Roberts: So, you can get a fracture of the testis, so the outside covering breaks open. That's normally with a huge blow to the testis. And it's one of the reasons why you try and protect your testes with a cricket box or whatever, if you're in high risk sports or activities. But that takes a huge blow, and it's pretty uncommon in kids. You do see it in adults, perhaps because they're more likely to take risk taking behaviours.

Host: We asked Dr Roberts what else might cause testicular pain or discomfort besides a blow, and when boys and men should see a medical professional for concerns about their testicles.

Dr Roberts: So, the injuries are really interesting. I'm a paediatric surgeon, and the thing that I see the most is pain associated with torsion, which is when the testis twists. Or, with a thing called a testicular appendage torsion.

Host: Because the testicles hang from a cord, it's possible that they can twist around inside the scrotum, which cuts off their blood supply. At the top of the testicle is a small tube-shaped structure called the testicular appendage. This can also get twisted and cause pain.

Dr Roberts: Testicular torsion happens before the age of 30 typically. After that, you're not at risk. In a baby, so in the first month or so of life, they can get a torsion event where the testis twists on its cord and blocks off the blood supply. And that twists outside of all those structures that are holding the testis together, so they all twist together. That's different than in an adult or in a post-pubertal boy where the testis twists inside all of the coverings. But in terms of the outcome, both of those events block off the blood supply to the testis, and the testis can die.

I've got about six hours between when the pain starts and when I need to get you to theatre before I can guarantee the survival of that testis. After that, the survival of the testis decreases. By about 24 hours, you maybe have a 5% chance of saving your testis. But it depends on how much it's twisted. So, if it's twisted three or four turns completely, then it's more likely to have blocked off its blood supply than if it's twisted 180 degrees or half a turn. So, the operation I do is to twist back the testis and fix it in the scrotum so it's much less likely to twist again.

Host: Testicular torsion is a very serious condition. So, is there anything that boys and men can do to prevent it from happening? Dr Roberts says unfortunately not, though some of the blame for torsion might lie in the way some people's testicles are formed.

Dr Roberts: We know that some boys have what are called bell clapper testes, that is the attachments to that cord are a little bit higher, so the testis is much more mobile, and it can twist on itself and then not be able to twist back. The reason for that happening, we don't quite understand as to why some boys have higher attachments and others lower attachments. But it evolves during that descent of the testis into the scrotum.

We know that if you've got a bell clapper testis on one side that you're more likely to have it on the other side. So, if you have an operation for a torsion, we'll fix both testes in place so that neither of them can twist again, because it's a significant risk; the idea of loss of a testis for most boys is a really big problem. And I say boys, but this can happen in post-pubertal boys and teenagers into their adulthood. But by the time you're about 30, you're much less likely to have it happen.

I also see boys with torsion that are much younger, so prepubertal. So, primary school age kids. But again, much more uncommon. They're far more likely to have a testicular appendage that's torted.

Host: Dr Roberts says that it's vital boys and men know that pain in their testicles could be a sign of testicular torsion, and that they should head to the hospital straight away.

Dr Roberts: I think one of the things that I get frustrated by is that we don't tell boys and men that they need to come to hospital straight away if they get a sore testis because of that very small time window. Six hours is not a lot of time by the time you've had the pain, told someone, and come to a hospital and been seen. And so, testicular pain for me is something that men have to go the closest emergency department straight away and have it assessed. And your GP will often send you to an emergency department anyway. So, getting in quickly is really important. It is actually an emergency.

Host: Testicular cancer is the second most common cancer in young Australian men, aged 18 to 39. Dr Roberts recommends young men get familiar with the normal look and feel of their testicles, and if anything changes, to tell their GP as soon as possible.

Dr Roberts: We know that about one in 190 men will have testicular cancer at some point in their lifetime, but we also know that more than 95% of those will be cured of their testicular cancer. And we know, again, the earlier that we intervene, the more likely you are to have a good outcome. So, being aware of changes in the testes, just like women have to be aware of changes in their breasts and do breast examination regularly, boys and men need to be looking at their testes regularly and examining them. They're looking for changes, lumps, bumps, pain, things that are unusual or different than they were previously. And rather than see those things and hope they go away, they should be going and seeing their GP promptly.

Host: She also says that it's not just lumps in the testicles men should be on the lookout for. Other changes in the body might be a symptom of testicular cancer.

Dr Roberts: One thing we didn't talk about with tumours is that it’s not just a lump they might present with, they might find it painful, that it's a bit swollen, it sits differently than normal – so any variation on normal is really important to note.

Because of the hormones that testis can produce if they've got cancers in them, you can actually get changes in your breasts as well. So, it’s really important if there were changes in their breasts to be conscious of that too. That's called gynecomastia.

If the GP's concerned that there's a lump or something unusual about it, they'll often do an ultrasound and a blood test. So, very straightforward easy things to do to give you a good answer. Again, all to reduce the risk of you having to have more therapy and to give you a really good outcome. Men who've had testicular cancer can go on and father children normally. So, it's not something that stops your life completely. You can have a normal life afterwards.

Host: Boys and men who have had a testicle removed because of testicular cancer or testicular torsion might choose to have a testicle implant put in place. Dr Roberts explained how she performs this operation.

Dr Roberts: If we take a testis out, some boys feel like they want to have a scrotum that looks symmetric, and they can have a prosthesis put in, which is a bit like a silicone implant that sits in the scrotum. But we wait until they've gone through puberty so that we can match the same size as the other testis, otherwise you're a bit lopsided.

So, they don't have to have an implant, it's just if they want to. And it's an egg-shaped, or testis-shaped silicone implant that we put in through an incision in the groin. So, up on the belly, and then we scoot it down in the same way that the testis descends down, so that it doesn't move around.

Host: Testicular cancer and testicular torsion are both serious but treatable conditions. For more information about both conditions, head to the show notes on our website.

The testicles are an important part of a man's body. So, what should Queensland men and boys be doing to look after their testicles? Dr Roberts says that preventing and treating infections and looking after your overall health are key steps to keeping your testicles healthy and promoting fertility if you're planning to have kids.

Dr Roberts: You can get infections within the testis and within the epididymitis, which is the tube that sits at the back of the testis to take all the sperm out. That's often referred to as epididymo-orchitis. Epididymis, epididymo, and orchitis, the testis is called the orchidor. So, that's the translation, essentially.

The infection most commonly in a boy will be a urinary tract infection that causes the infection. And in a sexually active boy, that is often a sexually transmitted infection, and often in men as well. The bugs track up from the urinary tract along the vas and into the epididymis and the testis that way. And they cause quite a bit of inflammation, so you get lots of redness and it's warm and it's painful, and quite a bit of swelling as well.

Sometimes they'll have the symptoms of urinary tract infection as well. So, they have painful urination and burning and stinging, but not always. And quite often, they'll have a fever. That needs antibiotics and it needs to be treated. And in the first instance, your GP's the right person to see.

In terms of fertility, protecting your fertility, we know that if you're a heavy smoker or you binge drink or drink alcohol heavily regularly, if you are obese, or if you're exposed to endocrine disruptors such as BPA regularly, that your fertility can be reduced. And so, having a healthy diet, reducing your exposure to alcohol, not smoking and keeping a normal weight is really important.

Host: While we had Dr Roberts in the room, we had to ask the most divisive question of all: boxers or briefs?

Dr Roberts: So, there's no evidence to suggest that one type of underwear's better than another. There have been a few studies along the way that have suggested this is better than that, but no consistent evidence. And so, it doesn't impact on fertility, I suppose it's just what's comfortable.

Host: Some men choose to alter the appearance of their testicles, either trying to make them seem larger or smaller, using cosmetic procedures like Botox injections or hanging weights from the scrotum which holds the testicles. Dr Roberts recommends men always consult a trained medical professional before undertaking any kind of procedure on the testicles.

Dr Roberts: Whatever you have done should be done by a medical practitioner who's trained and specialises in that. And there definitely are some medical indications for things like Botox in the scrotum, but that has to be done by someone who's well trained, who knows how to deal with the complications, because it's not without risk.

The scrotum sits in a muscle called the cremaster muscle. And the reason that it is contracted is sometimes to do with temperature and fear, and there are lots of different reasons why it contracts. If you stretch it, you're stretching essentially the skin, not the muscle. And so, it probably won't work that well, and it may well end up with some significant complications that then have to be dealt with. And so, if you have any problems, you're best to see a urologist and the GP in the first instance is probably the right person to see.

Host: Thank you for joining us for this episode of My Amazing Body. Before we go, did you guess this episode's Mystery Body Part? The set of body parts of which you might have two or many are your nipples! Congratulations if you guessed correctly.

My Amazing Body is brought to you by Queensland Health. With special thanks to our expert guest Dr Annie Roberts, the Queenslanders who answered our tricky testicle teaser questions, the media team at Children's Health Queensland and my podcast colleagues; Lauren our researcher, writer and producer, Carol our audio technician, Dan our music guru and Helen on sound effects.

Last updated: 21 October 2019