- Researchers have discovered a network of fluid-filled spaces surrounded by connective tissue that fill the spaces between our organs, surrounding and potentially protecting our interior throughout the body.
- In one study, scientists define this network as a new organ, the interstitium, of which they say it might be the largest organ in the human body.
- Understanding this network as an organ allows us to understand how diseases such as cancer spread and explain which healing techniques, such as acupuncture, work] It might look like we already identified all the structures in the human body, even if we did do not know the function of every cell and every organ.
But this assumption could be very wrong if the authors of a study recently published in the Nature Journal Scientific Reports are correct.
Between the spaces in our body – under the skin that lines the intestines and lungs, the blood vessels and the fasciae between the muscles – and more there is a fluid-filled tissue.
The idea that tissue and fluid are present in these spaces is not new; Interstitial fluid is one of the most important types of fluid in the body, although we did not know that it is contained in these structures.
But the authors of the new study say that this tissue has a uniform structure and function throughout the body that makes it an organ. With this definition, it could be the largest organ in the body that takes up more volume than even our skin.
This organ could help protect the rest of our organs and tissues. It could also explain the spread of certain cancers, as well as the development of a number of diseases in the body.
Finding a New Organ
Previously, the researchers thought that the area between other organs and tissues in our body is largely solid, consisting of structurally-supporting proteins known as collagen, as well as malleable elastin-binding proteins.
But an analysis using a newer type of imaging technology (called sample-based confocal laser endomicroscopy) revealed that interconnected fluid-filled sacs run through the collagen and elastin structures.
Previous attempts to view this tissue under a microscope made it impossible to see these connected fluid-filled spaces and the entire structure. The slicing caused the fluid to drain, empty the sacs and collapse, leaving the supporting proteins behind.
If you look at things in a new way, researchers can look at the structure of the tissue without it collapsing. This significantly changes our understanding of our interior, Neil Theise, a professor at the Department of Pathology and co-senior author of the study, stated in a press release.
The implications for all of this are enormous.
Functions of the Interstitium
It seems that the interstitium could have a unified function or functions. This could help researchers to decide if it really is an organ, as organs normally serve at least one particular purpose.
There are several ways in which the network of interstitial fluid and connective tissue can better explain how the human body works.
The fluid-filled sacs in this tissue could help the interstitial fluid move through the body. This is important because fluid in this network is the largest source of lymph, which is a critical part of the immune system.
"This finding has the potential to drive dramatic advances in medicine, including the potential for direct sampling of interstitial fluid to become a powerful diagnostic tool," Thise said.
A better understanding of this interstitial network could help us understand why skin wrinkles age in old age, why limbs become stiff, and how inflammatory diseases spread. It may also explain why cancer, which spreads into the space between organs, tends to appear in other parts of the body.
As something that surrounds our blood vessels and organs, the interstitium could help protect them from tearing, and it could help absorb shocks that could otherwise damage parts of our body. It is even possible that studying these spaces could help to reveal what acupuncture does in the body or not.
It takes time and research before the medical community decides whether to treat the interstitium as an organ or not.
But the possibility that this web of fluid and tissue is a completely new organ shows that we still have much to learn even in parts of ourselves that we believed to understand.