Mechanism of sperm transport unraveled

  A maze of small tubules in the mouse testis A maze of small tubules in the mouse testis. 3D fluorescence microscopy and tissue clearing (CLARITY) allow reconstruction of muscle cells within the walls of seminiferous tubules (red) and developing sperm nuclei (blue).

As sperm develop in the testis, the immature cells must make their way through a maze of small tubes known as seminiferous tubules. However, at this stage, the cells do not yet move the long tails that normally allow them to ‘swim’; it is therefore unclear how they are able to move through the tubules.

Now, Dr. David Fleck and Lina Kenzler (Institute for Biology II) have showed that, in mice, muscle-like cells within the walls of seminiferous tubules can create waves of contractions that push sperm along. Further experiments were then conducted on cells grown in the laboratory. This revealed that a signaling molecule called ATP orchestrates the moving process by activating a cascade of molecular events that result in contractions. Fleck, Kenzler et al. then harnessed an advanced microscopy technique to demonstrate that this mechanism occurs in living mice. Together, these results provide a better understanding of how sperm mature, which could potentially be relevant for both male infertility and birth control.

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