I remember when I first saw the pictures taken by the Hubble Space Telescope. Suddenly we could see amazing nebulas, the remains of supernova explosions and distant galaxies. They were there all along, but we just didn’t have the technology to see them.

New technology is reshaping how we see our bodies, too. We thought we had mapped out the human anatomy in all its detail… but now something has come along and showed us we were wrong.

That’s how doctors discovered a “new” organ in the human body that went undetected until now. And it’s not just a small organ tucked away in a little corner somewhere… it’s huge.

This Organ is Actually Your Biggest One

The newly discovered organ contains an amazing 20% of our body’s fluid.  It’s called the interstitium. And doctors stumbled upon it by accident.

The interstitium was identified by Dr. David Carr-Locke and Dr. Petros Benias of Mount Sinai-Beth Israel Medical Center in NYC1 in the course of using a new technology called pCLE (probe-based confocal laser endomicroscopy).

This amazing technology uses fiber-optics and low-power laser light to capture images from inside our cells. It means doctors can now see what’s happening inside the body without having to take a tissue sample and look at it under a microscope.

Drs. Carr-Locke and Benias were using it to study the bile duct of one of their cancer patients. They wanted to see if the cancer had spread.

They Had Never Seen Anything Like This Before

When they looked at the images from the cancer patient, they saw a network of fluid-filled cavities within a layer of tissue.

Surprisingly, when other doctors used pCLE to examine tissue in their patients, and in other parts of the body, they saw the same thing. Even in people who didn’t have cancer.

That’s when they realized this fluid-filled network of cavities runs throughout the entire body. Scientists and doctors couldn’t see it until now because when a tissue sample is examined under a microscope, it’s put between two slides, and that squashes the cavities flat.

But Now We Know it’s Just About Everywhere

Imagine a layer of microscopic bubble wrap that sits under the top layer of your skin. It’s also in the tissue lining of your muscles, lungs, gut and even blood vessels. But instead of the bubbles being arrayed in symmetrical rows and filled with air, they’re randomly laid out and filled with fluid. That gives you an idea of where the interstitium is and what it looks like.

The walls of the interstitium are made of collagen, a connective tissue.  Scientists used to believe there was a collagen “wall” under the skin and around the organs. But now they see the collagen is actually filled with pockets of fluid.

A Vast Network That Interconnects Different Parts of Our Body

That means the collagen isn’t so much a wall as a roadway that carries fluids throughout our body.2

In fact, the interstitium is how lymph fluid travels around our bodies.  The “new” organ also distributes nutrients throughout our tissue.  And on a negative note, the interstitium roadway is also an avenue by which cancer spreads from one area to others.

There’s still a lot to learn about the interstitium. At this stage, scientists believe it plays a role in cushioning our bodies like a shock absorber. And they also believe there’s a way to use the interstitium to treat diseases like cancer because it can distribute protein, antibody, and other types of therapies.3

This exciting discovery is also causing some debate within the medical community. Some people feel it can’t be considered an actual “organ.”  But so far most experts seem to be in favor of it.  Organ or not, it’s clear the interstitium opens up new possibilities that are worth exploring.

  1. https://www.livescience.com/62128-interstitium-organ.html
  2. https://www.webmd.com/a-to-z-guides/what-is-the-interstitium
  3. https://www.ncbi.nlm.nih.gov/books/NBK53446/