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Anatomy · General anatomy and histology: Weibel-Palade bodies
Sample itemElectron microscopy of an endothelial cell shows rod-shaped membrane-bound granules with parallel tubules. Which substance do they mainly store?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
D. Von Willebrand factor with P-selectin
Weibel-Palade bodies are endothelial storage granules for von Willebrand factor and P-selectin. They release their contents on endothelial activation to promote platelet adhesion and leukocyte rolling.
Option by option
A. Heparin and histamine
Heparin and histamine are stored in mast cell granules.
B. Fibrinogen and thrombin
Fibrinogen circulates in plasma and is made by the liver; thrombin is formed from prothrombin.
C. Prostacyclin and nitric oxide
Prostacyclin and nitric oxide are synthesised on demand, not stored in granules.
D. Von Willebrand factor with P-selectin (correct)
Correct. Weibel-Palade bodies store von Willebrand factor and P-selectin.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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