Medical

Did scientists really just discover a new organ in the human body?

Did scientists really just dis...
A new study suggests the interstitium could be an entirely new human organ
A new study suggests the interstitium could be an entirely new human organ
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Seen beneath the top layer of the skin, this is an artist impression of the interstitium (Credit: Illustration by Jill Gregory. Printed with permission from Mount Sinai Health System, licensed under CC-BY-ND)
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Seen beneath the top layer of the skin, this is an artist impression of the interstitium (Credit: Illustration by Jill Gregory. Printed with permission from Mount Sinai Health System, licensed under CC-BY-ND)
A new study suggests the interstitium could be an entirely new human organ
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A new study suggests the interstitium could be an entirely new human organ

Using a new microscopic technique, a team of scientists has identified a previously unknown human anatomical feature. Dubbed the interstitium, the discovery reveals that what was previously thought to be simply dense connective tissue sitting below the skin's surface, and surrounding our organs, is actually a complex series of interconnected, fluid-filled compartments.

The discovery came when a couple of researchers were experimenting with a new type of endoscope that uses a laser and fluorescent dyes to examine living tissue at a microscopic level while probing patients. While examining a patient's bile duct, the researchers identified a pattern of cavities that didn't fit with the known anatomy of the bile duct.

The duo took their anomalous results to pathology expert Neil Theise and the team devised a process to take bile duct biopsies in a novel way without dehydrating the samples. As Theise explains to ResearchGate, "Rather than process the sampled bile duct tissue as usual, with dehydration and chemical fixation to make slides, we quickly froze the tissue, keeping the resected piece as close to the normal living tissue as possible."

The revelation was that what was previously assumed to be just dense connective tissue was in fact an interconnected network of tiny fluid-filled cavities supported by a lattice meshwork of collagen and elastin proteins. Because prior microscopic analysis involved some degree of cellular dehydration these spaces had never been accurately identified, although traces were known and simply assumed to be just artifacts of processing.

"We would often see little "cracks" between collagen bundles in these layers," says Theise. "I was taught, and in turn taught many of my trainees, that these cracks were artifacts of processing. We had pulled the tissue too hard in preparing the slide and separations had formed. But these were not artifacts: these were the remnants of the collapsed spaces. They had been there all the time. But it was only when we could look at living tissue that we could see that."

Seen beneath the top layer of the skin, this is an artist impression of the interstitium (Credit: Illustration by Jill Gregory. Printed with permission from Mount Sinai Health System, licensed under CC-BY-ND)
Seen beneath the top layer of the skin, this is an artist impression of the interstitium (Credit: Illustration by Jill Gregory. Printed with permission from Mount Sinai Health System, licensed under CC-BY-ND)

After identifying this surprising space in the bile duct it was quickly seen across the entire human body, from the linings of organs to the fascia surrounding muscles. The interstitium was found to be a kind of pre-lymph system draining fluid into the body's vital lymphatic systems.

The implications of the research are fascinating with Theise suggesting that the interstitium could be a fundamental force in driving cancer metastasis as well as offering a biological explanation for the reported efficacy of techniques such as acupuncture.

But perhaps the most controversial suggestion of the research is that the interstitium should be classified as a new organ. Theise suggests the interstitium fits all the criteria for the definition of an organ, potentially making it the 80th organ to be classified in the human body.

"The definition of 'organ' is imprecise, but usually implies that there is a unity and uniqueness of structure or of function," says Theise. "This space has both: unique properties and structures not seen elsewhere and functions that are highly specific and dependent on the unique structures and cell types that form it."

But not everyone is convinced. While the discovery of the interstitium is inarguably a significant scientific achievement that could lead to a new understanding of the human body, a huge amount of research is yet to be done to determine its function and how it affects the rest of our body. Michael Nathanson, from the Yale School of Medicine, was not involved in this new research and is skeptical of the "organ" designation.

"I would think of this as a new component that is common among a variety of organs, rather than a new organ in and of itself," says Nathanson in an interview with CNN. "It would be analogous to discovering blood vessels for the first time, in that they are in every organ but they aren't an organ themselves."

Despite the semantic argument over classification, the discovery of this new anatomical feature is undoubtedly important and it highlights with exciting clarity that we still have so much more to learn about how our complex human body functions.

The research was published in the journal Scientific Reports.

Source: NYU School of Medicine

7 comments
judahis
Trained in the sciences from bachelor's to Master's to the PhD level (Columbia College, University of Wisconsin-Madison and Milwaukee), medical writer for the WARF Foundation at UW-Madison and later medical writer for Modern Medicine Magazine, I say let us not be too muddled in nomenclature but more interested in the function of this new discovery, whether called "organ" or not. This is what functional and authentic science is all about: Not taking what is "known" for granted but continuing to explore and "fine tune" what we think we know. Congratulations to the researchers and future researchers.
BrianK56
It will be interesting to hear if the fluid filled spaces heal after being cut open during surgeries. Just as interesting will be finding the makeup of the fluid and the role it plays in human health.
javadog
Yes it will be fascinating to learn all the places where interstitium is located, what cells populate it, the metabolism and biochemical transport mechanisms, and what diseases result when various functions go awry.
ljaques
See? I told you that despite all the technology, doctors are still in the Dark Ages when it comes to the human body. Pain, colds, flu, HIV, MRSA...should I go on?
amazed W1
But don't hold your breath, Javadog and Ijaques. Remember how long it took for the commonest causes of stomach and gastric ulcers to be accepted by the medical profession. They stubbornly held onto "stress" as the sole cause when it was obvious that the incidence in groups of friends and aquaintances suggested some kind of infective "agent", from virus to parasite.
janine
The structure and chemistry of this "new organ" has been explored and ignored for 100 years. See Reckeweg and the extra-cellular matrix. In simple terms, it detoxifies acidic cellular waste.
john75
If the vascular system isn't considered a seperate organ where it isn't within another it certainly should be. It's like concluding roads must only have local signifigance because most houses have driveways. But the exact terminologies do distract from importance, as with Nathanson. Perhaps recovery from everything from open heart surgery to surgical repair of sports injuries like ACL/MCL tears would progress faster if these channels are more closely reconnected when grafted or reconnecting tissue. It also seems likely that the number and distribution of these voids may not be uniform from one area to another within a person much less between individuals and may offer an explanation and predictor for significantly different outcomes.