Baby Gap

Life is full of give and take – cells and tissues exchange chemicals with each other, often pushing them through tiny channels in cell membranes. There is another way though, making use of the gaps where cells meet in the epithelium – the skin-like barrier that coats many of our tissues – but what controls this paracellular transport is a little mysterious. Here a mesh of epithelial cells (purple) nestles a developing egg cell in a fruit fly ovary. Pictured under a confocal fluorescence microscope, the cells form triangular junctions that expand or contract to create temporary intercellular spaces (green), long enough for yolk-forming proteins to squeeze through to the egg. With a similar mechanism helping chemicals move from the blood into mammalian testes, future work may unravel the role of paracellular transport in human fertility and development too.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Jone Isasti-Sanchez and colleagues
• Institute of Animal Physiology, University of Münster, Münster, Germany
• Image copyright held by the original authors
• Research published in Developmental Cell, April 2021