We often think of bone as something that is structurally firm, especially its hard outer layer, called cortical bone.
But a new discovery has never seen hidden passages that pass through these rigid organs in both animals and humans. leads to a rethinking of the structure and function of the basic skeletal anatomy.
In a new study, researchers in Germany report a previously discovered undetected network of fine blood vessels that act as a secret tunnel system inside the bones, helping blood and immune cells to spread efficiently and quickly throughout the body.
"It is indeed unexpected to find a new central anatomical structure that is not described in any textbook in the 21
These small channels called "transcortical TCVs  may be new to science, but they help explain how emergency drug infusions introduced for the first time on the battlefield can quickly revive the wounded soldiers.
In such emergencies, medics do not always have the time or the opportunity to find or
"Despite the evidence of the presence of complex blood supply in the bones, the molecular mechanisms and anatomy that underlie these rapid cell and fluid changes the bone marrow in the bloodstream has remained elusive, "explains a commentary on the new study.
Now the root of this mechanism is blown away, as it was previously noticed a few years ago.Gunzer studies a fluorescent color the blood cells in mice and observed them under the microscope, seeming to pass through what should be hard bone
Incapable of discovering something in the medical literature to explain the phenomenon, he developed a new research project. 19659002] In the new study, Gunzer's team uses a chemical called ethyl cinnamate on mice, tibia (bone bones) to "clear" the bones, making them transparent.
Then, using a combination of LSFM and X-ray microscopy, they have been able to detect for the first time several hundred of these small TCVs passing through the cortical layer of the bones. According to researchers, a mouse tibia may contain more than 1,000 of these small capillaries, and amazingly enough, the team says that over 80% of the arterial and 59% of the venous blood passes through the canals .
That's a lot of blood. is "I have never seen such vessels," said RALF Mueller, a research scientist at the Swiss Federal Institute of Technology, who did not participate in the study.
"But we have never looked that way, so it's a surprise to me … it will surely need some replication in other laboratories."
When the team examines human anatomy by depicting the bone of a volunteer foot (Gunzer himself), they found evidence of the same type of TCV structures, although they were thicker, and researchers admit that more work is needed to their exact function is confirmed.
As to how these hidden passages faded from our message until now, the team says the breakthrough is related to technological advances in the image, but they admit they are even surprised by the unexpected result.
"There is still a lot of insanity to learn about human anatomy," said Gunzer Scientist . "We found blood vessels in a new place we did not know before. "
The discovery – reminds of another secret tunnel system in the skull discovered by a Harvard study last year – Collaboration
" Since key bone pathologies are related to changes in the TCV system, "the authors write, the authors present all kinds of new medical articles for the study of inflammatory diseases, tissue injuries, cell migration or simply understanding how the blood is flowing. "Their article," Completely new research opportunities that further characterize the role of TCVs in skeletal biol ogy and disease can be predicted. "
The results are reported in Nature Metabolism .