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Sperm don't swim anything like we thought they did, new study finds

sperm swimming in a corkscrew motion
The sperm tail moves very rapidly in 3D like a rotating drill bit, not to-and-fro as 2D microscope data suggested.
(Image: © polymaths-lab.com)

Under a microscope, human sperm seem to swim like wiggling eels, tails gyrating to and fro as they seek an egg to fertilize. 

But now, new 3D microscopy and high-speed video reveal that sperm don't swim in this simple, symmetrical motion at all. Instead, they move with a rollicking spin that compensates for the fact that their tails actually beat only to one side. 

"It's almost like if you're a swimmer, but you could only wiggle your leg to one side," said study author Hermes Gadêlha, a mathematician at the University of Bristol in the U.K. "If you did this in a swimming pool and you only did this to one side, you would always swim in circles. … Nature in its wisdom came [up] with a very complex, ingenious way to go forward." 

Related: Sexy swimmers: 7 facts about sperm

Strange swimmers

The first person to observe human sperm close up was Antonie van Leeuwenhoek, a Dutch scientist known as the father of microbiology. In 1677, van Leeuwenhoek turned his newly developed microscope toward his own semen, seeing for the first time that the fluid was filled with tiny, wiggling cells. 

Under a 2D microscope, it was clear that the sperm were propelled by tails, which seemed to wiggle side-to-side as the sperm head rotated. For the next 343 years, this was the understanding of how human sperm moved. 

"[M]any scientists have postulated that there is likely to be a very important 3D element to how the sperm tail moves, but to date we have not had the technology to reliably make such measurements," said Allan Pacey, a professor of andrology at the University of Sheffield in England, who was not involved in the research. 

The new research is thus a "significant step forward," Pacey wrote in an email to Live Science. 

Gadêlha and his colleagues at the Universidad Nacional Autónoma de México started the research out of "blue-sky exploration," Gadêlha said. Using microscopy techniques that allow for imaging in three dimensions and a high-speed camera that can capture 55,000 frames per second, they recorded human sperm swimming on a microscope slide. 

"What we found was something utterly surprising, because it completely broke with our belief system," Gadêlha told Live Science. 

Related: The 7 biggest mysteries of the human body

The sperm tails weren't wiggling, whip-like, side-to-side. Instead, they could only beat in one direction. In order to wring forward motion out of this asymmetrical tail movement, the sperm head rotated with a jittery motion at the same time that the tail rotated.The head rotation and the tail are actually two separate movements controlled by two different cellular mechanisms, Gadêlha said. But when they combine, the result is something like a spinning otter or a rotating drill bit. Over the course of a 360-degree rotation, the one-side tail movement evens out, adding up to forward propulsion.

"The sperm is not even swimming, the sperm is drilling into the fluid," Gadêlha said. 

The researchers published their findings today (July 31) in the journal Science Advances.

Asymmetry and fertility

In technical terms, how the sperm moves is called precession, meaning it rotates around an axis, but that axis of rotation is changing. The planets do this in their rotational journeys around the sun, but a more familiar example might be a spinning top, which wobbles and dances about the floor as it rotates on its tip. 

"It's important to note that on their journey to the egg that sperm will swim through a much more complex environment than the drop of fluid in which they were observed for this study," Pacey said. "In the woman's body, they will have to swim in narrow channels of very sticky fluid in the cervix, walls of undulating cells in the fallopian tubes, as well have to cope with muscular contractions and fluid being pushed along (by the wafting tops of cells called cilia) in the opposite direction to where they want to go. However, if they are indeed able to drill their way forward, I can now see in much better clarity how sperm might cope with this assault course in order to reach the egg and be able to get inside it," Pacey said

Sperm motility, or ability to move, is one of the key metrics fertility doctors look at when assessing male fertility, Gadêlha said. The rolling of the sperm's head isn't currently considered in any of these metrics, but it's possible that further study could reveal certain defects that disrupt this rotation, and thus stymy the sperm's movement. 

Fertility clinics use 2D microscopy, and more work is needed to find out if 3D microscopy could benefit their analysis, Pacey said. 

"Certainly, any 3D approach would have to be quick, cheap and automated to have any clinical value," he said. "But regardless of this, this paper is certainly a step in the right direction."

Originally published in Live Science.

  • Valentine Michael Smith
    It means men didn't pay attention, and thought they knew everything. Again.
    Reply
  • Psuedo-Pseudo
    Uh, wrong. It means suspicions of complexity we didn't understand were confirmed with the development of new *scopy techniques.

    Science is constantly evolving, being "wrong" isn't a result of not "paying attention" really. Your anti-science spiel is misplaced.

    Valentine Michael Smith said:
    It means men didn't pay attention, and thought they knew everything. Again.
    Reply
  • Bigtime
    If it had been up to women, there wouldn't be any science at all and mankind would still think that babies came from fairies and coconut shells lol

    Valentine Michael Smith said:
    It means men didn't pay attention, and thought they knew everything. Again.
    Reply
  • annefrance
    Valentine Michael Smith? Boy, are we ever old! You make me nostalgic for one of the best novels I ever read by one of the most prolific sci-fi authors ever. Pseudo-Pseudo simply doesn't grok that your funny comment is not meant to be "anti-science" at all.
    Reply
  • James2k20
    It's amazing, isn't it? 3.5 centuries of believing you knew something and you didn't actually know it at all. The best know that what we think we know today could be proven false tomorrow. The ones to steer clear of: the worse, the least wise, the ones who treat science like a religion repeat theories as fact and throw about terms such as "anti-science" or "if you knew basic science" or "believe in science" to anyone who dares question them.
    Reply
  • cecilia fx
    Bigtime said:
    If it had been up to women, there wouldn't be any science at all and mankind would still think that babies came from fairies and coconut shells lol
    really? tell that to all the scientists who happen to be women.
    Reply
  • sagitarriatjefferspin
    annefrance said:
    Valentine Michael Smith? Boy, are we ever old! You make me nostalgic for one of the best novels I ever read by one of the most prolific sci-fi authors ever. Pseudo-Pseudo simply doesn't grok that your funny comment is not meant to be "anti-science" at all.
    Props to Heinlein!
    Reply
  • Alexandru Boris Cosciug
    Motto: “Sperm motility, or ability to move, is one of the key metrics fertility doctors look at when assessing male fertility, Gadêlha said. The rolling of the sperm's head isn't currently considered in any of these metrics, but it's possible that further study could reveal certain defects that disrupt this rotation, and thus stymy the sperm's movement.” (from the article)
    ……………..
    I bring here my comment made in 2010 on:
    https://www.the-scientist.com/the-nutshell/sperm-motility-secrets-revealed-43507Sperm motility secrets revealedReproductive biologists have identified the mechanism that triggers sperm's race to the egg, reports a study in Cell today. Stained sperm cells(Blue, nucleus; red, mitochondria; green, Hv1protein localized in the sperm flagellum) Image: Yuriy KirichokBy measuring the electrical current passing through the sperm cell membrane, researchers at the University of California, San Francisco, identified a channel that releases a flood of protons from a sperm cell, initiating its trip up the fallopian tubes.Cassandra Brooks - Feb 3, 2010
    My observation
    : all comments on The Scientists were eliminated in march 2018, but I keep it in my computer.
    alexandruI appreciate all the genetic research. The man shall reach the total knowledge.
    How long will you enjoy pouring scorn on knowledge? Will you never learn?” (Proverbs 1.22)
    According to my studies, exposed in four books, the man, attention please! - male and female -, is the materialized according to the information which is contained in Adam mtDNA, existed only in xifoid process, called one of the man's ribs (Genesis 2.21), or sternum peak called double edged sword peak, to where soul and spirit meet, to where joints and marrow come together (Paul, Hebrews 4.12 - the best description in the world).
    Lev Tolstoi - *The bad part is that people of medicine dealing with the body more than soul.* (Last years journal / About God and man)
    The only real problem for The Scientist is to understand the soul feedback.
    Stephen Hawking: *What is it that breathes fire into the equations and makes a universe for them to describe? ... Then we shall all, philosophers, scientists, and just ordinary people, be able to take part in the discussion of the question of why it is that we and the universe exist. If we find the answer to that, it would be the ultimate triumph of human reason - for then we would know the mind of God. * (A brief history of time)
    Henry Schaefer - *The significance and joy in my science comes in the occasional moments of discovering something new and saying to myself, 'So that's how God did it!' My goal is to understand a little corner of God's plan.* (U.S. News & World Report, Dec. 23, 1991)
    .....................
    In the computer language, the soul is called soft. However, the new machine is wireless controlled, and the internal soft is subordinated to an external programme, which realise a whole harmony. Because the scientist explanation of the unknown facts, looks like:
    *it is possible and probable*, I said, using the same technique: *It is sure that Adam mtDNA exists in the xifoid process, one of man's ribs and it is sure that Eve mtDNA is a copy of Adam mtDNA, produced during ovogenesis process, controlled by Adam mtDNA. (Genesis 2.22) *
    In 2007, I developed a new theory about human body internal communication based on the mitochondrial bio-electromagnetic transducers. According to Paul, Hebrew 4.12 I identified in xiphoid process a pair of bio-magnetic receptor that recognizes all kind of the microbial molecule. According to this theory, a couple of Adam mtDNA and Eve mtDNA, that contain all genome data, exist in the xiphoid process and communicate with all internal organs. Because this couple memorizes all the process data, it is possible that it influences the immune system with negative or positive feedback, according to the information sent by the brain.
    Abstract: Adam mtDNA inheritance - ISBN 978-606-92107-1-0
    The necessary and sufficient processes to a well function of the human body are meticulous arranged by specific organizational cells, so called process bio-managers, using inter-conditioned procedures, transmitted through three ways of communication: chemical or protein channel, electrical or ion channel and mitochondrial or electromagnetic field wireless channel. The third type is out of the visible and measurable spectrum and raises a new challenge to the scientist. For this type of bio comunication we bring a new theoretical hypothesis, based on the managerial multidisciplinary analysis of a cybernetic model proposed by us, by simulating the human body function with the virtual computerized system based on the management of its total knowledge and its perfect quality way of function. The main bricks used for this virtual construction are: the brain, as main bio-processor, and Eve mtDNA and Adam mtDNA, as bio-antennas.
    This assembly of the total knowledge, build with brain reasoning, biological feeling, and unlimited soul feeling, is called by us main decision triangle, IQ-EQ-CQ.
    The main principle of the management of the total knowledge imposes us to not neglect the information produced by man during the time, even if it seems creasy at the beginning (see brainstorming definition). Because in the natural fertilisation the spermatozoids are naturally equipped with the paternal mtDNA (it looks like reflex klystron power amplifier, KPA = a veritable main bio-GPS), we consider that the paternal mitochondria DNA have a very important role in the evolution of the human being life quality and we have developed a new hypothesis, Adam mtDNA theory in addition to Eve mtDNA theory.
    Keywords: brain, mitochondria, maternal, paternal
    Reply
  • Valentine Michael Smith
    Psuedo-Pseudo said:
    Uh, wrong. It means suspicions of complexity we didn't understand were confirmed with the development of new *scopy techniques.

    Science is constantly evolving, being "wrong" isn't a result of not "paying attention" really. Your anti-science spiel is misplaced.

    I made an anti-male spiel, nigga.


    annefrance said:
    Valentine Michael Smith? Boy, are we ever old! You make me nostalgic for one of the best novels I ever read by one of the most prolific sci-fi authors ever. Pseudo-Pseudo simply doesn't grok that your funny comment is not meant to be "anti-science" at all.

    Somehow I missed the notification of your quote...or it didn't get sent?...... In any case, SF. Scifi/Sci-fi equals fantasy in space. Skiffy - as in iffy.




    I birthed after these events.
    Reply
  • Hayseed
    It's just another example of nature's dynamic. A helix. A curved/closed helix has a non-pi ratio. Planetary orbits are helical. Stellar orbits in galaxies are helical. A closed helical rotating structure could physically explain the density, mass, and quantum of charge. Such a structure has two perpendicular rotations.(accelerations)

    For nature to be so consistent, everywhere, for so long......it has to be simple.
    Reply