Weibel-Palade bodies

Weibel–Palade bodies are the storage granules of endothelial cells, the cells that form the inner lining of the blood vessels and heart. They store and release two principal molecules, von Willebrand factor and P-selectin, and thus play a dual role in hemostasis and inflammation.

Weibel–Palade bodies were initially described by the Swiss anatomist Ewald R. Weibel and the Romanian physiologist George Emil Palade in 1964. Palade won Nobel Prize in Physiology and Medicine in 1974 for his work on the function of organelles in cells.

There are two major components stored within Weibel–Palade bodies. One is von Willebrand factor (vWF), a multimeric protein that plays a major role in blood coagulation. Storage of long polymers of vWF gives this specialized lysosomal structure an oblong shape and striated appearance on electron microscope. The other is P-selectin, which plays a central role in the ability of inflamed endothelial cells to recruit passing leukocytes (white blood cells), allowing them to exit the blood vessel (extravasate) and enter the surrounding tissue, where they can migrate to the site of infection or injury.

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