Revealed: The Secret of the Sperm's Wild Dash to the Egg

By Smriti Rao | February 7, 2010 8:41 am

spermWhen it comes to a sperm fertilizing an egg, it all comes down to speed and timing. If the sperm starts swimming at top speed too soon, it will die before it reaches the egg. But if it swims too slowly then it won’t get to its destination in time. Now, scientists have discovered a system in the sperm that acts like a gas pedal, causing the sperm to swim faster as it gets closer to the egg. The findings were published in the February issue of Cell.

Researchers already knew that the speed of a sperm depends on its pH, or its internal acidity levels. The less acidic and more alkline it is, the faster it swims. They also knew that a sperm doesn’t sprint at top speed for its entire trip through a woman’s reproductive tract. It travels relatively slowly for the first part of its journey, and then gets lodged in the sticky folds of the fallopian tubes, resting until another, still unknown signal raises their pH again. This initiates their final race to the egg. “It’s a tough job for a sperm — when it’s deposited it has to travel a long distance to the egg sites,” [said Dejian Ren, who was not involved in the new study]. “This process has been known for many decades, but how it actually happens remained a mystery” [The Scientist].

Now the researchers say they’ve found the mechanism that raises a sperm’s pH and kicks it into high gear. In order to increase its pH and become more alkaline, the sperm needs to jettison protons, and the US scientists have found pores on its surface which allow it to do precisely that. Dr Yuriy Kirichok, who led the research, said: “The concentration of protons inside the sperm cell is 1,000 times higher than outside. If you just open a pore, protons will go outside – we identify the molecule that lets them out” [BBC].

The scientists found that as the sperm got closer to an egg, they react to a substance called anandamide, which is present in the female reproductive tract. That is when these pores or Hv1 proton channels, open–releasing protons and making the sperm swim faster. Gaining a better understanding of what prompts sperm to spring into action could open doors toward developing effective male contraception, or, alternatively, ways to give “slow swimmers” a jolt [Time].

And since anandamide is an “endocannabinoid,” this may explain why male marijuana smokers can have fertility problems–the cannabinoids found in marijuana may mimic the effect of the natural substance. Dr Kirichok said: “Marijuana likely activates sperm prematurely, leaving them burnt out in a matter of hours” [BBC].

For more info, check out this video of the researchers from the University of California in San Francisco talking about the proton activation.

Related Content:
80beats: Did Researchers Really Grow Human Sperm from Stem Cells?
80beats: Older Fathers’ Sperm May Produce Children With Slightly Lower IQs
80beats: Testicles Could Yield Stem Cells Without the Ethical Complications
80beats: Men Have a Biological Clock, Too

Image: iStockphoto

CATEGORIZED UNDER: Health & Medicine
  • NewEnglandBob

    Maybe NASA can use this technique too. Proton drive rockets!

  • Mark

    Sounds like if you have slow swimmers try smoking some marijuana. I don’t see how we can keep a plant that has so much to do with are bodies as far as cannabinoid receptors, but under federal law it cannot be even researched for some odd reason maybe money is to blame…

  • Bryan

    Interesting. Um.. Mark, I’m all for Cannabis legalization and you’re right.. along w/ millions of others that Cannabis is a miracle drug the government doesn’t know how to make money off of in all Cannabis’s variety of commerce, so instead they stick w/ Big Pharm cause they can count on that money regardless of that fact Big Pharm is often placibo’s or damaging to the body…and while we humans should have the right to put in our bodies what we prefer, which can be safer. Yeah, the government’s looking out for.. us…

    obviously biased but thought provoking to say the least.

    Oh, and Mark, while Cannabis make actually have a positive effect on the male reproductive system (MMJ RESEARCH would HELP…bump FED.GOV.)This article referred to Marijuana possibly contributing to “slow swimmers”.

    (And since anandamide is an “endocannabinoid,” this may explain why male marijuana smokers can have fertility problems–the cannabinoids found in marijuana may mimic the effect of the natural substance. Dr Kirichok said: “Marijuana likely activates sperm prematurely, leaving them burnt out in a matter of hours” [BBC].)

    However, it would appear that Cannabis could perhaps be a natural PIECE OF THE PUZZLE towards Birth Control. If FED.GOV. would allow further RESEARCH ADVANCEMENT, we could very well find that Cannabis could be a natural form of Birth Control for men to administer, even w/out “stoned” sensations..
    That’s right.. Big Pharm and their con⋅tra⋅cep⋅tive’s would struggle and go down.
    A Natural MALE con⋅tra⋅cep⋅tive?? in coordination w/ unexpected safe sex mishap..

    Anyways, Mark, no offense, careful w/ your article reading. Mistakes happen. No worries.

    Be Wise, Legalize.


    Apologies for any ignorance or negativity.

    God Bless.

  • Ian

    Amazing! This incredible series of events, makes me realise just how awesome new life is.

    It’s a great shame then that one of the applications of this research should be contraception.

  • Phil E. Drifter

    Mark, it’s a catch-22 by Uncle Sam; they outlawed it and put it as a Schedule 1 substance which means ‘high potential for abuse and no medicinal value,’ which means they refuse to accept any valid studies showing it in fact does have medicinal properties.

    It was outlawed to replace outlawed slave labor with prison labor. It’s to keep minorities suppressed.

    What dangers? Does Yahagi have any proof? Because the AMA fought outlawing cannabis until Harry Anslinger started having doctors arrested after they defended this wonderful plant, causing them to drop their support of this medicine. Recently however they have renewed their interest in having tests done to show it’s validity as an all-natural medicine, as opposed to the synthetic chemicals Big Pharma creates in labs.

    It’s not a war on (some) drugs it’s a war on minorities to replace outlawed slave labor with prison labor, read

    “Well, there it was, you didn’t have to look another foot as you went from state to state right on the floor of the state legislature. And so what was the genesis for the early state marijuana laws in the Rocky Mountain and southwestern areas of this country? It wasn’t hostility to the drug, it was hostility to the newly arrived Mexican community that used it.”

  • Rain

    Ian. What is wrong with the fact that this could cause advancements in contraception? It would be awesome if there was a way for a ‘male pill’ to exist, without it actually being hormonal and thus potentially damaging male fertility in the end, or causing moobies or something. Men would be more likely to adopt something that has no physiological side effects but instead makes their sperm too lazy to get anywhere while they are using it.

    For women to finally be given a break from being responsible for contraception would be really good and it is only fair, too.

    Just because new life can be created, does not mean that it should be. People have the right to determine if they want to have children, and they have a right to have sex only for the sake of intimacy, and pleasure. Sperm and eggs are only alive in the way an amoeba is alive. Until they fuse, they are not even a complete cell, so in fact an amoeba is more sophisticated in a way.

  • Chris the Pragmatist

    Little proton booster rockets for sperm and if triggered too soon sperm run out of fuel. Pretty cool research if you ask me and yes I see future advancements in contraception due to this discovery. That they were amazed that female enzymes or hormones triggered the reaction to swim faster by sperm is a bit silly. The sperm had to react because of something, so it was only logical that the trigger came from the source of our little soldiers affections. The closer he gets the faster he swims because the egg is chemically beckoning to him!!!

    Now, what may be a bit preposterous but wouldn’t surprise me is if geneticists and scientists tried to isolate certain sperm from reaching the egg that they have determined to be unwanted (something in the DNA pattern of the sperm reveals a defect of some sort such as Down’s Syndrom, in the male genome etc). I wouldn’t be surprised to hear of such research coming out eventually, as far fetched as it may seem.


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