Mindful movement people have suspected it. Chinese medicine has known it for millenia. And since 2018, western medicine has a name for it: the interstitium. The November 17, 2023 episode of Radiolab has finally brought it to a wide audience.

The episode is based on Jennifer Brandel’s article “Invisible Landscapes.” We’ve had the notion that our connective tissue is inert and only serves as a barrier. Thanks to advances in seeing living tissue through a microscope, scientists like Dr. Neil Theise have seen that the interstitium is a dynamic, honeycomb-shaped network with tubes and fluids.

It might be hard to imagine an organ woven throughout our entire body. And it is; according to Dr. Neil Theise:

“The dermis; the wrappings of all your muscles and your bones; the collagen that wraps around every artery and every vein; the collagen that gives structure to every visceral organ: your lungs, your heart, your liver, your kidneys, your pancreas, your GI tract; the fibrous coverings inside your skull around your brain; the fibrous coverings going into the brain and out of the brain,”

are infused with interstitium. But it’s more than a system; the tissue is unique and identifiable, which is one way of identifying an organ.

Another way of identifying an organ is through function, and science is on the cusp of this. It’s mysterious, but here’s what we know:

• 25% of our body fluid resides in the interstitium.
• The interstitium moves four times more fluid through the body than the vascular system does.
• The fluid carries a recently-discovered type of cell.
• It can be seen with the naked eye during surgery.

I’m very excited about giving connective tissue the importance and care it deserves. I’ve based my yoga practice and teachings on more than biomechanics: Yin Yoga highlights Chinese meridians, and Fascial Release practices are almost completely outside any mainstream yoga system. I hope this changes with this Radiolab release and this new vocabulary, and we can all get to know this wondrous, newly-minted organ.