A corkscrew-like structure in the tip of sperm tails has been identified by researchers at the University of Gothenburg, Sweden. Researchers think the structure could help sperm to swim quickly and in the right direction.
In the study, researchers were able to view 3D images of individual structures within human sperm thanks to a new imaging technique called cryo-electron tomography. The method involves flash-freezing biological samples, thinning them out and imaging with a powerful electron microscope.
'Since the cells are depicted frozen in ice, without the addition of chemicals which can obscure the smallest cell structures, even individual proteins inside the cell can be observed,' explains study lead author Johanna Höög from the University of Gothenburg's Department of Chemistry and Molecular Biology.
When the researchers looked at detailed images of the very tip of the tail they discovered a structure that had never been seen before.
'[We spotted] a spiral that stretched in from the tip of the sperm and was about a tenth of the length of the tail,' says Davide Zabeo, a PhD student at the University of Gothenburg who carried out the research.
The researchers speculate that the corkscrew structure interferes with the growth of microtubules – the biological structure that helps cells maintain their shape. This could allow the sperm's energy to be channelled into swimming quickly towards the egg.
This discovery provides important insights into how sperm's structure affects its ability to move. It could lead to new treatments for poor sperm mobility – a major cause of infertility in men. It's hoped that the research could eventually pave the way for a new contraceptive method or drug to help infertile men.
The study was published in the journal Scientific Reports.