Friday Weird Science: the ins and outs of erections

Believe it or not, for this Friday’s weird science, I wanted to get AWAY from sex. Do something different. But then the boys at Deep Sea News decided to have their sex week, and then Joanne at Joanne Loves Science decided to interview Mary Roach (without ME!!! What were you thinking, Joanne. Sci is so hurt…but she couldn’t really ask all the good questions because it’s for middle school age…), and well, I have to do SOMETHING sex related, right? Of course right.
And, well, penises are funny looking. There’s that, too.

ResearchBlogging.org Deng et al. “Real-time three-dimensional ultrasound visualization of erection and artificial coitus” International Journal of Andrology, 2006.
I would have loved to see the advertisements for this study: “Men needed between ages 18-65 for study of erection and coitus. Must have no history of erectile dysfunction. Ability to get it on with a Jell-O mould a plus.”


It’s well established that genitalia are interesting. Sometimes amusing, sometimes embarrassing, but always interesting. However, for all that we have fifty million words for “penis”, “sex”, and “hard-on”, there are actually still doubts about how things like erection actually WORK. What we do know are the basics:
During erection, there is increased blood flow to the penis, and decreased blood flow out. The penis has cavities (known as corpus cavernosa) that run parallel to the urethra, and these cavities contain tiny microvessels. So when there is increase blood flow in, and decreased blood flow out, blood will pool in the microvessels, causing a stiffening of the penis. Full rigidity also requires the perineal muscles to contract. Looks like this:
deng 2006 2.png
So we know the basics of HOW, but most studies on male erection have looked at autopsies and other such observations. It’s a pretty hard (hehe, hard) phenomenon to see in action. Attempts have been made (some successful) to look with MRI, but it’s very difficult, as you have to hold VERY still to get a good MRI picture, and it’s hard for an erection, when held perfectly still, to…stay hard. Most of these studies end up having the men involved rely on a good dose of Viagra, and so the results aren’t entirely natural. And even with the Viagra, most men in MRI scanners fail to achieve full orgasm.
What you need is another scanning technique. One that will allow for a little movement, to keep the stimulation going. Studies on erections, if you could get data in real time, could go a long way to helping understand the underlying cause of erectile dysfunctions, things that might be missed by MRIs taking still pictures. So this study decided to use 3-D ultrasound to see what they could get. Using real-time volummetric imaging, with relatively little movement, you can get some pretty clear pictures.
But there are still some issues. First, you don’t want the ultrasound right ON the penis if you can help it. Aside from movement issues, the probe can deform soft tissue to a certain extent, and since you’re working with some tissue that can be VERY soft at times, you want to acoid that. So these authors made a special gel bath, to serve as an artificial vagina. Basically, participants got to make mad, passionate love to a Jell-O mould. Behold:
deng 2006 1.png
To get the idea of what this looked like, you have to think of the guy lying face down, with the ultrasound beneath him.
And it turns out that it worked pretty well! Only one guy failed to achieve an erection after 30 minutes (even with “visual stimulation”), but he was the unlucky participant that was subjected to a water bath rather than the Jell-O. Also the participants tested with gel artificial vaginas achieved full erection and even orgasm within about 5-10 minutes. The only thing the authors COULDN’T get was the actually footage of ejaculation, as movement then because too erratic and the ultrasound equipment was drowned out by the noise. This is too bad, because an image of that would be the first time anyone has ever seen ejaculation occur from the inside in real time.
But they still got some good pictures:
deng 2006 3.png
Is that detail or what! Right now to the pubic hair! This is the first figure of an erect penis, and the images are clear enough for you to see the corpus cavernosa (what’s the plural of that? Corpus cavernosae? Corpa Cavernosa?), as well as the deep artery with feeds the body and glans of the penis, the urethra, and the corpus spongiosum along the bottom. On the outside (bottom right) you can even see the veins.
And they got to watch an erection in action:
deng 2006 4.png
The top panel here is a penis just erected. You can see on the left the corpus canvernosa only half-filled, and the glans is still flush with the body of the penis, and not yet protruding fully. The lower panel shows a full erection, with cavernous spaces fully filled, and the inner septum of the penis clearly visible.
So why did they do this study? Well…to see if they could. This preliminary study will allow people to use these methods to study problems like erectile dysfunction in the future, and it’s the first time a gel matrix was used as an artificial vagina to allow for detection via ultrasound. And with the addition of color Doppler, you can look at blood flow to the penis in great detail, to find potential problems and changes with pharmacological treatments. With any luck, detection methods will allow for more and more erratic movement, and some time in the future, we may see ejaculation from the inside!
I bet it looks funny.
DENG, J., HALL-CRAGGS, M., PELLERIN, D., LINNEY, A., LEES, W., RODECK, C., & TODD-POKROPEK, A. (2006). Real-time three-dimensional ultrasound visualization of erection and artificial coitus International Journal of Andrology, 29 (2), 374-379 DOI: 10.1111/j.1365-2605.2005.00617.x

18 Responses

  1. With any luck, detection methods will allow for more and more erratic movement, and some time in the future, we may see ejaculation from the inside!
    The movement doesn’t need to be more erratic, just more erotic. ๐Ÿ˜‰

  2. 5-10 minutes. That gel mould would have had something to say about the study participants to its friends, I bet.
    Sorry, I just couldn’t resist. It’s actually quite an interesting study.

  3. Mmm, Jell-O… So how does one get involved in these studies?๐Ÿ™‚

  4. We’ll just tell your mom we ate the Jell-O.

  5. “And, well, penises are funny looking.”
    Speak for yourself, lady!

  6. The word truncated will never be the same for me.

  7. I would have been perfectly happy to have you on a road trip to see Mary. And yes, many apologies for not allowing Mary to go on and on about sex, it’s just that while I love it too, best to keep it all G rated in case my fledgling followers parents should run across the site. Feel bad to hinder Mary’s expression! lol!
    In my histology course, I have traumatized many young males by requiring them look at the inner workings and morphology of the penis. Wonder if it destroyed any libidos, at least temporarily.
    You do know Mary is on TED talks this week, right? 10 things you didn’t know about orgasm!

  8. Hey! Mary Roach here. Did you guys know that I’ve met the man who owns that penis? It’s Jing Deng, who did the 4-D scan of me and Ed for BONK. He confessed to me that he did the Jello-bonking himself. Our scan is up on his page too, but it doesn’t look very 4-D. It’s a movie though. Fun!
    Enjoyed your article!

  9. EEEEEEK!!!!! MARY ROACH IS ON MY BLOG!!!!
    *phew* Sorry. Love your work! I’ve done a lot of Friday Weird Science from the bibliographies of your books. Unfortunately I forgot to attribute this one.
    That’s a really amusing thing to know. I mean, how many times can you look a random photo (or 3-D ultrasound), and say “hey, I know that penis!” I know the study did mention having trouble finding participants, and I can’t say that I’m too surprised. I’m definitely going to have to check out his website…
    Thanks so much for stopping by! Can’t wait to see what you put out next!

  10. EEEEEEK!!!!! MARY ROACH IS ON MY BLOG!!!!

    LOL! I was also like ZOMG!!!It’s Mary Roach herself!!!! (Hi Mary! Love your writing!).
    You’ve hit the big leagues Sci. I’ll be waiting for your book!

  11. “I know the study did mention having trouble finding participants, and I can’t say that I’m too surprised.”
    I was wondering if the 5-10 minutes was typical, or just typical of the guys they could get to volunteer…

  12. I will never be able to look at Jell-O the same way again.
    Especially if it has whipped topping.

  13. “During erection, there is increased blood flow to the penis, and decreased blood flow out.”
    Tell me about it, less blood for the real head to think. I am glad the centered text was corrected, that made everything hard (no not that kind of hard) to read. Love your Friday posts and your sense of humor.

  14. Getting naked with a bowl of jello? They’ll rue the day.

  15. “there are actually still doubts about how things like erection actually WORK.”
    You scientists are really funny with all of your gadgets. Using scanners to find out how an erection works.
    Did you ever think of investigating your own penis to find out how erections work?
    Those of us out here in the real world know all about how an erection works. But we don’t mind waiting years for you scientist to put your official stamp on what we already know.

  16. one lan๐Ÿ˜€

  17. Corpora Cavernosa. Fairly certain about it, too.

  18. This is a pretty interesting study. A lot of people giggle when it comes to research on sex but it is just like analyzing other aspects of the body. Professional athletes get analyzed and scrutinized for things like shoulder rotation. If it can get that technical for sports, why not study sex and see how people could make it better for themselves.
    I just wanted to leave a comment to say that your blog is appreciated and I learned a couple of things today.

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