Secret Brain Tunnels, 2

The research team began examining the skull very carefully, looking at it from all angles, trying to figure out how neutrophils—a specific type of immune cell, which are among the first to arrive at an injury site—were getting to the brain. Unexpectedly, they discovered tiny channels that connected the bone marrow directly with the outer lining of the brain. With the help of advanced imaging techniques, they watched neutrophils moving through the channels. Blood normally flowed through the channels from the skull’s interior to the bone marrow, but after a stroke, neutrophils were seen moving in the opposite direction to get to damaged tissue. The skull bone marrow apparently assumes a special role in fighting inflammatory diseases of the central nervous system. Because of its close proximity to the brain, the skull bone marrow can provide a supply of these immune system cells directly through these tiny channels quite quickly—if everything is working properly, of course.