When our brains are affected by injury or inflammation, our immune system comes into effect.
The white corpuscles that help the brain are produced in the bone marrow, and until recently the researchers thought they would flow to the brain through the bloodstream.
However, new research shows that the auxiliaries are much closer to the brain: they leave the bone marrow that is in the skull.
Shortcut in your skull
The discovery was made by a Harvard Medical School research team in the US. The scientists applied a dye to the bone marrow of the legs and skull of mice. The mice were then inflicted a slight brain injury.
The experiments showed that most immune cells moved from the skull to the affected spot in the brain, and that they took a direct route and did not end up in the bloodstream first.
Scans of the inside of the skulls show a few 22 micron holes that allow the white blood cells to pass through.
Immune cells quickly reach the brain injury via channels in the bone marrow of the skull.
Scans of human skulls then showed that we also have such channels. With us the holes are 77 micrometres in size. According to the scientists, they play the same role with us as with the mice.
The new discovery can lead to new methods for getting drugs to end up in the brain faster.