This week, scientists reported the existence of a supposedly new human organ.
But some experts said this new organ is actually old news.
"The interstitial tissue is a part of every organ, just as blood vessels and lymphatic vessels are part of every organ," said Melody Swartz, a professor at the Institute for Molecular Engineering and the Ben May Department for Cancer Research at the University of Chicago. "They have long been recognized to be fluid-filled and that fluid can move within the interstitial space."
In fact, there are hundreds of studies about these spaces, and their connection to lymphatic vessels, Swartz told BuzzFeed News. She said that researchers study the interstitium in live animals and people using fluorescent tracers and other means. In other words: Its existence is well-known.
She also said the interstitium can't be considered an organ on its own because the tissue is found in all organs and there's no evidence that they are connected. For example, the interstitium of the mesentery, the fold of tissue that attaches your gut to your abdominal wall, is not connected to the interstitium of the skin, she said.
"I strongly feel that this paper has been grossly misrepresented both by the authors and the press," she said.
Helge Wiig, a professor of physiology at the University of Bergen in Norway, who has studied and published continuously on the interstitium for decades, said in an email that "much of what is presented in the actual paper as novel is old textbook knowledge and should not create a buzz."