A new imaging technique allows researchers to follow the agile, elusive male reproductive cell.
By Emily Elert Posted 09.18.2012 at 2:29 pm 11 Comments

Sperm Up Close Joyce Harper, UCL, Wellcome Images

Sperm are small, but they're quick—an individual sperm can wiggle through a space 25 times the length of its body in a single second. (For comparison, a human would have to swim 120 miles per hour to achieve the same relative speed.)

The sperm's combination of tininess and agility makes them almost impossible to track, since researchers have to zoom way in with their microscopes to see the frenetic flagellates at all (think of following a fast-flying bird through binoculars, except moreso).

That's where Aydogan Ozcan (one of PopSci's own Brilliant Ten!) comes in: the UCLA engineer has developed a method to record the motion of individual sperm cells using a "lens free" imaging platform.

To track the sperm, Ozcan and his team positioned two LEDs—one red, one blue—at a 45-degree angle with each other, and pointed them at a sample gamete-filled fluid. When the multi-directional, multi-colored lights illuminated the sperm, they cast holographic shadows—shadows that can be reconstructed to obtain 3-D images—which Ozcan recorded and processed.

The technique allowed the researchers to track the motion of about 15,000 sperm cells simultaneously. The team found that, rather than moving forward in a straight line, about 5 percent of sperm swim in a small helical, or corkscrew, pattern. Perhaps more surprising was that almost all (about 90%) of the helical swimmers spun to the right.

In their paper, which came out this week in PNAS, the authors did not venture a guess as to why sperm stick to swimming in a right-handed spiral rather than a left-handed one. They did mention that the new technique will be helpful for tracking lots of other microorganisms, as well as testing the effects of various chemicals and drugs on the swimming habits of sperm.

The trajectory of a sperm swimming in a right-handed corkscrew pattern:  Aydogan Ozcan/UCLA

Note: The original story said that a human would have to run 540,000 mph to achieve the same relative speed as a sperm. In response to comments from readers, that number has been corrected to 102 mph

11 Comments

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CeilingFan124
09/18/12 at 2:51 pm

How in the world did you get 540,000 Mph equivalent? Convert 540,000k mph to f/s and you get 792,000 ft/s. Divide by 25 and you get that the human body is 31,680ft long. Haha. Hope im wrong here.

If you assume a body is 6ft long, and it could travel 25 times that distance in 1 second... thats 150ft/s. which equals 102.273mph, not 540,000mph. Am i missing something here?

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Bufu23
09/18/12 at 2:58 pm

Interesting.. about 90% swim to the right...

Its estimated that about 10% of the population is left handed.. maybe that says something about how and why? Numbers add up...

* I’m living the future so the presence is my past *

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JayArr
09/18/12 at 3:23 pm

@CeilingFan124, you are correct. The author forgot to divide by 5280ft/mile when she made her calculations. She gave us 540,000 feet travelled in 1 hour... LOL

Hurray for mathematics! Ohhh, and fast spermies.... :)

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macro820
09/18/12 at 6:29 pm

Bufu23 that was my thought exactly, it could be possible as they said 90% swam right and between 70-95% are right handed

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Raiderfan0224
09/18/12 at 8:27 pm

Actually, she said that only 5% swim in a helical patern. Of that 5%, 90% (or 4.5% of the total number) swam to the right only. More misconceptions..

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msr042377
09/19/12 at 9:24 am

I wonder if they spin in the opposite direction in the southern hemisphere due to the Coriolis effect.

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Dublin992233
09/19/12 at 1:36 pm

Researchers found that by going left, they would have to wait at signal lights to cross traffic. Therefore they go right as it's more time efficient when delivering packages...

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iowa46
09/19/12 at 2:58 pm

Note: sperm goes its length 25X second. Emily, you would have to wriggle 25X your body length each second. If running your upright body width (which is how most humans get around) you would maybe be 18 inches times 25 per second, or 37.5fps or about 25.6mph.

5% of the 15,000 sperm swam in the corkscrew pattern, which yields 750 sperm, of which 90% of which 675 were right handed turners and 75 lefties. What about the 14,250 other sperm cells?

A little more clarity would be appreciated.

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EmilyElert
09/20/12 at 4:38 pm

Thank you @CeilingFan124 for pointing my error! @JayArr is exactly right—I forgot to convert to mph from fps. And @iowa46 makes an excellent point too—it makes more sense to talk about how fast a human would have to swim, rather than how fast they would have to run.

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Hernberger
09/20/12 at 8:57 pm

"I'm sure lots of people can't turn le--... I'm sure there are other people out there that can't turn to the l---... There's got to be someone else out there that can't turn left..."

Apparently sperm has the same disability as Derick Zoolander. Good ol' Leftitis.

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sethmoiger109
09/21/12 at 10:56 pm

Suggested answer; Re; why a small % corkscrew; the head of a sperm is flat and oval, which stabilizes it as it moves through liquid. And in the majority of sperm, the nucleus is located in the center of the head of the sperm, causing its mass to be centered/stabilized. On a small % of sperm, an abnormality causes either a) the nucleus to form slightly off center, de-stabilizing it, causing the corkscrew motion or b) the cell membrane to the right of the head of the sperm (the right side of the oval) forms slightly shorter in width, causing it to corkscrew (like an airplane with part of a wing missing will corkscrew).

The reason the motion is right handed, is this particular abnormality most often occurs on the right side of the sperm. Just one person's opinion.



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