Researchers have identified a network of fluid-filled spaces surrounded by connective tissue that fills the spaces between our organs, surrounding and potentially protecting our insides throughout the body.
In a study, scientists define this network as a new organ, the interstitium, which they say could be the largest organ in the human body.
Understanding this network as an organ could help us understand how diseases like cancer spread and it help explain what healing techniques like acupuncture are tapping into.
It might seem like we should already have identified all the structures in the human body, even if we don't know the function of every cell and organ.
But that assumption might be very wrong, if the authors of a study newly published in the Nature journal Scientific Reports are correct.
In between the spaces in our bodies — beneath the skin, lining the gut and lungs, surrounding blood vessels and fascia between muscles, and more — there's a fluid-filled network of tissue.
The idea that there's tissue and fluid in these spaces isn't new; interstitial fluid is one of the significant types of fluid in the body, though we didn’t know it was contained in these structures.
But the authors of the new study say this tissue has a unified structure and function throughout the body that makes it an organ. Using that definition, it could be the largest organ in the body, taking up a bigger volume than even our skin.
This organ might help protect the rest of our organs and tissue. It could also explain the spread of certain cancers, as well as how a number of diseases progress in the body.
Finding a new organ
Researchers previously thought the area between other organs and tissues in our body was largely solid, comprised of structural supportive proteins known as collagen, as well as stretchier elastin connective proteins.
But an analysis using a newer kind of imaging technology (called probe-based confocal laser endomicrosopy) revealed that interconnected fluid-filled sacs run through the collagen and elastin structures.