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.
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.