Blood clot on a plaster

Anne Weston, London Research Institute, Cancer Research UK

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Scanning electron micrograph (SEM) of the underside of a sticking plaster that has been used to treat a razor blade cut. Red blood cells and thin fibres of the protein fibrin, coloured beige, can be seen between the gauze fibres of the plaster, which is coloured blue-grey.

How does blood clot?

When a blood vessel is cut, the damage immediately activates platelets in the blood, causing them to become 'sticky'. The platelets clump around the site of the cut and recruit blood proteins called clotting factors. These clotting factors initiate a number of reactions with other chemicals and proteins in the blood, which results in the conversion of clotting factor I (fibrinogen dissolved in the blood) into fibrin, a solid protein that plugs the wound. In this SEM, the fibrin can be seen as thin, beige fibres. These fibres trap blood cells and platelets to form a solid clot, which not only prevents further bleeding but also protects the open wound from infection.

What did the judges like about this image?

The blood on the plaster is image creator Anne Weston's. She cut her finger on a razor blade and put a plaster over it, which immediately became soaked with blood and had to be replaced. She imaged the first, discarded plaster in a scanning electron microscope out of curiosity. Anne remarked: "The Wellcome Image Awards seems to be recognising how clumsy I am. Last year, an image of my scalded hand won; this year, it's my cut finger!"

James Cutmore of BBC 'Focus' magazine says: "The image as a whole is very detailed and clear - you can see the way the tiny red blood cells seem to cling to every part of the structure. When you learn that the blood is the microscopist's, it really adds something. It's one of those pictures that truly intrigues people, because it shows an everyday occurrence in a completely unexpected way. The plaster looks so different at this scale compared to how it looks to us in real life."