What is it about?

The vas deferens is the tube that carries sperm during ejaculation. It is usually described as a muscular tube that contracts to push sperm forward, but exactly how this happens inside the living body has been difficult to see. We first looked at the entire vas deferens in 3D rather than examining it only as individual tissue sections. This revealed something that was difficult to recognize from conventional images: toward one end of the duct, the passage progressively narrows and becomes highly folded and almost closed, forming a valve-like structure. We then watched this region in a living mouse and found that it dynamically opens as sperm-containing fluid arrives, allowing sperm to pass through.

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Why is it important?

This changes the way we think about the vas deferens. Rather than being simply a pipe that squeezes its contents forward, it is a dynamic organ that changes its own shape to control transport. More broadly, the study shows how much biological information can be missed when an organ is viewed only as thin slices. By combining whole-organ 3D imaging with live imaging, we were able to connect structure with function – revealing not only what the tissue looks like, but how it actually works. Similar principles may apply to many other tubular organs in the body that need to control the movement of fluids or cells.

Perspectives

My favorite part of this study was discovering something that had been in front of us all along. Traditional cross-sectional images clearly show that the vas deferens has a highly folded inner surface, but they do not tell us how those folds are organized along the full length of the organ. When we imaged the entire ~1.5-cm duct in 3D, the picture suddenly became much clearer: the lumen gradually narrowed into a collapsed, valve-like region. That observation immediately raised another question—does this structure actually move? Live imaging then allowed us to watch it open as sperm flow arrived. For me, this is a nice example of how changing the way we look at a biological system can reveal a completely different level of organization and function.

Tsuyoshi Hirashima
National University of Singapore

Read the Original

This page is a summary of: Flow-driven lumen remodeling and valve opening in the vas deferens, Proceedings of the National Academy of Sciences, September 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2538135123.
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