Which type of capillary is characterized by large gaps between endothelial cells and is seen in the liver and bone marrow?

• A. Discontinuous (sinusoidal) capillary
• B. Continuous capillary
• C. Fenestrated capillary
• D. Nonfenestrated capillary

Answer: (A)

The main concept here is how capillaries differ in permeability. The type that has large gaps between endothelial cells is the discontinuous (sinusoidal) capillary. These wide intercellular gaps, plus a discontinuous basement membrane, allow easy passage of large molecules and even blood cells between the blood and surrounding tissue. That’s why you see them in the liver and bone marrow, where substantial exchange and transit of cells and plasma components are needed. In contrast, continuous capillaries have an intact, tight endothelial lining with minimal gaps, and fenestrated capillaries have pores that permit more flow but still maintain a basement membrane and narrower pathways.