BIOLOGY Volume 2 - A Guide to General Biology - 2004

14. TRANSPORT IN ANIMALS

14.3. Blood Composition

14.3.3. Platelets (Thrombocytes)

In mammals, platelets are irregularly shaped, membrane-bound Cell fragments that generally lack a Nucleus¹. They are produced from specialized Bone Marrow Cells. Each platelet is roughly four times smaller than a red Blood cell. Platelets are essential for initiating the blood-clotting process. There are approximately 250,000 platelets per 1 mm³ of blood. The lifespan of human platelets is 5–9 days, after which they are destroyed in The Liver and Spleen.

¹ In some vertebrates, these are small nucleated cells. — Trans.

Last update: 06/08/2026

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