Much of the fluid flow inside lymph nodes occurs in blood capillaries
No bigger than peas but numbered in the hundreds, your lymph nodes defend against infection. Blood vessels within lymph nodes allow immune cells and fluids to pass into them from the blood. Harmful pathogens in these fluids are concentrated in the nodes where they can be neutralised. The flow of fluid is known to occur partly through blood vessel walls. To better understand this process, researchers captured a detailed picture of blood vessels in mouse lymph nodes using micro-CT (pictured). They found small blood vessels called capillaries accounted for 75% of the surface area of blood vessel walls. These capillaries were largely around the node periphery. Next, they used mathematical modelling to predict fluid flow in lymph nodes, finding most occurred in the periphery where capillaries would be found. This gives us a clearer picture of how fluid flows inside lymph nodes.
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