Our bodies are full of bacteria. Most are harmless or even helpful but some that invade from the outside world are on the hunt for vulnerable tissues to attack. Viewed from above, these Escherichia coli (E.coli) cells are lurking like purple Zeppelins over a green-coloured surface similar to living tissue. A high-powered microscope highlights the contours of each cell, picking out the details of this mock invasion in 3D (colours have been applied artificially to enhance the dramatic effect). Each bacterial invader – measuring 50,000,000 times smaller than a Goodyear blimp – has attached itself to the surface below with long, anchor-like fibres. As more bacteria latch on, the invasion force gathers – soon they will engulf the surface from view completely. Inside our bodies, a similar scene might warn of only hours until an attack – until the bacteria swoop down on our own cells and clash with our waiting immune defences.
Written by John Ankers
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.