Small, colourless, irregular blood cell crucial in coagulation. Produced in bone marrow and stored in the spleen, platelets accumulate to block a cut in a blood vessel and provide a surface for fibrin strands to adhere to, contract to pull the strands together, and take part in the conversion sequence of coagulation factors. They also store and transport several chemicals.

Variants of PLATELET

platelet or thrombocyte

This entry comes from Encyclopædia Britannica Concise.
For the full entry on platelet, visit

Seen & Heard

What made you look up platelet? Please tell us what you were reading, watching or discussing that led you here.