Windows on Windows

Your cheap waterproof coat looks impenetrable, but when the rain comes you realise it's formed of a million imperceptible holes through which water can freely flow. Such is the structure of your liver’s blood vessels, though the tiny gaps in the vessel lining, fenestrae, serve a more useful purpose – to allow essential molecules to pass between blood and liver tissue. These crucial windows are too small for conventional light microscopy to look at, but a new technique has provided a clearer picture. Researchers infused a dye through a mouse liver (yellow in the vessel wall section pictured, with magenta also marking lining cells and confirming the dye has taken hold in the right place) then examined sections with a newly enhanced form of microscopy called super-resolution optical-sectioning structured illumination microscopy (OS-SIM). Seeing these structures in situ will help scientists study how these tiny molecular sieves change during disease.

Written by Anthony Lewis

Anthony Lewis

Writer

Ant was the web editor in the early days of BPoD, and has since worked with the UK’s top science organisations as a writer and multimedia producer. He now splits his time between freelance work and managing multimedia at The Lancet.

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• Image from work by Jasmin C. Schürstedt-Seher and colleagues
• Biomolecular Photonics, Faculty of Physics, Bielefeld University, Bielefeld, Germany
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY-NC 4.0)
• Published in bioRxiv, August 2026 (not peer reviewed)