Despite referring to sperm as “sperms”, this paper showing 3D tracking of human sperm swimming paths is pretty cool. Actually, I take that back. Calling them sperms definitely adds to the awesomeness. I won’t pretend to fully understand the physics behind their method, but it’s obvious that this imaging method will be important for many other things besides looking at sperm (which is already hugely important IMHO).
Most of the sperm they studied swam in a kind of squiggly straight line, while a small proportion swam in a tight helix while also moving forward in a straight line. The most interesting thing about the sperm that swam in a helix pattern was that seminal plasma (the fluidy part of the semen) tended to prevent helical swimming. However, tubal fluid (from fallopian tubes) tended to encourage it. What exactly that says about how sperm swim IRL, we still don’t know.
The first question I would like to see this method used to answer is: do sperm from fertile men swim differently than sperm from sterile men? This would be especially interesting in cases where the cause of infertility is unclear (because the sperm otherwise seem normal).
For more about this article, you can read this piece on the National Geographic website (but please ignore the references to sperm as microorganisms. Yes, they’re micro, but no, they are not organisms. That would be weird.)
- Sperm captured in 3D for first time reveals corkscrew swimming patterns (gizmodo.com)
- Glucose ramps up sperm speed (nittygrittyscience.com)
- Drosophila sperm swim backwards in the female reproductive tract (plosone.org)
Su TW, Xue L, & Ozcan A (2012). High-throughput lensfree 3D tracking of human sperms reveals rare statistics of helical trajectories. Proceedings of the National Academy of Sciences of the United States of America PMID: 22988076