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Only the most advanced technology has just allowed scientists to see something that was always there: an interstitial space “unidentified” until now, full of liquid cavities, present inside and between the tissues of our body. A group of experts qualifies it as a new body.
Those who discovered it define it as “a new expansion and specification of the concept of the human interstice”, something that traditionally in biology referred to the space between the cells and tissues of the organism.
Paradoxically, the “interstitium” could become one of the largest organs, next to the skin: scientists estimate that this network of collagen and elastin cavities filled with liquid would agglutinate more than a fifth of all the fluid in our body.
He was identified by a team of pathologists from the School of Medicine at NYU University, in the United States, who has just published his results in the journal Scientific Reports .
The experts concluded that these interstitial layers of our organism, previously thought to be formed by a dense and solid connective tissue, are actually interconnected with each other, through compartments filled with liquid.
These tissues are under the skin, line the digestive tract, lungs and urinary system and surround the arteries, veins and fascia, a structure of connective tissue that extends throughout the body.
Researchers believe that this “anatomical structure” may be important in explaining cancer metastasis, edema, fibrosis and the mechanical functioning of many or all of the tissues and organs of our body.
How had they not seen him until now?
With the standard methods of visualization of the human anatomy these structures are not perceived.
The scientists were able to identify this new “organ” thanks to the technological advances of the endomicroscopy in vivo , which shows in real time the histology and structure of the tissues.
But the finding was a surprise.
Copyright image JILL GREGORY / MOUNT SINAI HEALTH SYSTEMImage caption
As detailed in their study, the team of researchers made in 2015 an operation for which they used a laser endomicroscopy , a technology called Confocal Laser Endomicroscopy (pCLE), to examine the bile duct of a patient affected by cancer.
And after an injection of a dye called fluorescein they saw “a reticular pattern with sinuses (holes) full of fluorescein that had no anatomical correlation.”
But when they wanted to examine them on the microscopic plates of the usual biopsy they had disappeared.
After doing several tests, Neil Theise, senior co-author of the study, realized that the conventional process of fixing tissue samples in plates drained the fluid from the structure.
Normally scientists treat the samples with chemicals, cut them into a very thin layer and apply dye to highlight the key features.
The team discovered that the drainage of fluid causes the network of compartments filled with liquid to collapse, like the floors of a building, and that “for decades has appeared as something solid in the biopsy plates, ” said Theise. , from the pathology department of NYU Langone Health.
By changing the biopsy technique, his team managed to preserve the “live” anatomy of the structure, “demonstrating that it is part of the submucosa and that it is an interstitial space filled with fluid not previously appreciated “.
Thus, “wide and dark branched bands surrounded by large and polygonal spaces filled with fluorescein” are described, they describe in their report.
For this study, the scientists confirmed the existence of these structures in 12 other operated patients.
What is its function?
Copyright of the GETTY IMAGES imageImage caption
According to the researchers, until now science has not studied either the flow or the volume of the interstitial fluid of the human body.
The identification of this “interstitial space” feeds several hypotheses.
Experts believe that this network of interconnected spaces, strong and elastic, can act as a buffer to prevent the tissues of our body from tearing with daily functioning, which causes the organs, muscles and blood vessels to constrict and expand constantly .
In addition, they believe that this network of cavities is like a highway for fluids in motion. And that could justify the idea that when a cancer reaches the interstitial space it can spread through the body very quickly, in what is known as metastasis.
On the other hand, the authors believe that the cells that form the interstitium change with age, and can contribute to wrinkling of the skin and hardening of the extremities, as well as the progression of fibrotic, scleroid and inflammatory diseases.