Back to Basics 5: WEIRD SCIENCE EDITION!

Aug 27 2010 Published by under Basic Science Posts, Friday Weird Science

Yup, you knew it! Let's go back to basics. Let's talk about ERECTIONS.

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:

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:
(Mary Roach told me at one point that she MET one of the test subjects who did this, he's apparently an author on the paper. The things people do for SCIENCE).

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:

Is that detail or what! Right down 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:

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

2 responses so far

  • arnsholt says:

    The plural of "corpus cavernosum" is "corpora cavernosa", since you asked. Corpus is a neuter (with slightly strange declination) so the plural ends in -a. Plurals in -ae are feminines (which usually end in -a in the singular).

  • Alteredstory says:

    I love studies like this - it's so cool!

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