So Do I Have a New Organ or What?

My beautiful organ. Illustration: Jill Gregory/Mount Sinai Health System

Apparently, I have a new organ. You do too. Maybe.

In a study published in the journal Scientific Reports on Tuesday, researchers concluded that a network of fluid-filled spaces that’s located under the skin and surrounds our blood vessels and muscles and organs, is in fact its own organ called the interstitium. That’s it up there, labelled “Fluid filled space.” But the thing is, experts can’t agree on whether it’s really an organ or not.

Dr. Neil Theise, professor of pathology at NYU Langone Health in New York, and a co-senior author of the study, says the interstitium is definitely an organ, because organs are usually defined as “a tissue with a unitary structure,” or “a tissue with a unitary function,” and the interstitium has both. If it is an organ, it would be our biggest, comprising about 16 percent of our body mass.

Thiese told CNN he thinks we may have missed the interstitium before, because traditionally, tissue samples that are examined under a microscope have been dehydrated, which would have collapsed the fluid in the organ and made it difficult to see. But a new technique called confocal laser endomicroscopy allowed researchers to see where all the fluid accumulated and according to Thiese, “Once you see it [the interstitium], you can’t unsee it.”

Dr. Michael Nathanson, however, a professor of medicine and cell biology and chief of the section of digestive diseases at Yale University School of Medicine, said to think of the interstitium more like blood vessels, “a new component that is common among a variety of organs, rather than a new organ in and of itself.”

Organ or not, researchers believe the interstitium might play a role in a variety of conditions and treatments. The spaces are where tattoo ink lives, for example, and where the tip of the needle goes during acupuncture. They could also serve as a conduit for cancer cells, which “raises the possibility that direct sampling of the interstitial fluid could be a diagnostic tool,” researchers wrote.

“We are optimistic that with what we learned, we’ll soon be able to study and target the interstitial space for diagnosis of disease and perhaps for novel personalized treatments,” Thiese told CNN.

Anyway, congratulations to all of us on our beautiful new (maybe) organs.

So Do I Have a New Organ or What?