Platelets, or thrombocytes, are the cells in your blood responsible for making clots. After a clot is made to stop up a puncture or wound in a blood vessel, the clot shrinks – this makes it denser and more effective, but also means that it is less likely to obstruct bloodflow.
The exact mechanism of the shrinking has only recently been witnessed for the first time. The platelets (shown above) extend small projections known as filopodia that latch on to fibres made of the protein fibrin in the blood. The filopodia then expand and contract repeatedly to draw the fibres closer together, causing the clot to contract.
The research is described in Nature Communications.