The tail of the sperm is formed by thousands of small blocks of protein called tubulins, which form larger structures in the form of tubes called microtubules. The function of tubulins is to provide the necessary energy so that the sperm can be propelled towards its target.
Using a technology called cryoelectronic tomography, which allows to freeze microscopic structures and take images of them in 2D, the Swedish researchers tried to study in detail the tail of the sperm. And that's how they discovered in microtubules the existence of spiral-shaped structures that nobody had seen before.
But what are they for? That's something that researchers still do not know for sure, although they suspect that these propellers, which have been dubbed TAILS (acronym in English of tail axoneme intra-lumenal spiral), can act as a barrier to prevent tubulins from developing. abnormal shape, preventing the sperm from swimming.