Larger Inside

Like Doctor Who’s TARDIS, the gastro-intestinal tract – the tube running from your mouth to your bottom – is much bigger on the inside than it appears from the outside, and the entire surface area of this vital pipework is roughly the same as a small one-room flat. This impressive size is mostly due to microscopic ‘fingers’ called microvilli on the surface of cells in the small intestine – the purple frond-like structures in this image of human intestine cells, seen down a high-powered microscope. The green spots are clumps of a molecule called ANKS4B, which organises the microvilli into small clusters so they can function properly to absorb nutrients from food. Intriguingly, similar molecules are at work inside the inner ear, clustering together stereocilia – the hair-like fronds that convert soundwaves into nerve signals our brains interpret as sound – highlighting how similar processes are used around the body to get the job done.

Written by Kat Arney

Kat Arney

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Dr Kat Arney is an award-winning science writer, broadcaster and public speaker, and is the founder and Creative Director of First Create The Media.

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• Image from work by Scott W.Crawley and colleagues
• Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
• Image copyright Elsevier 2016
• Published in Developmental Cell, January 2016