Your body now has an extra organ. Researchers have classified a brand-new organ inside our bodies, one that's been hiding in plain sight in our digestive system this whole time.

Although we now know about the structure of this new organ, its function is still poorly understood, and studying it could be the key to better understanding and treatment of abdominal and digestive disease. Known as the mesentery, the new organ is found in our digestive systems, and was long thought to be made up of fragmented, separate structures. But recent research has shown that it's actually one, continuous organ.

The evidence for the organ's reclassification is now published in The Lancet Gastroenterology & Hepatology.

"In the paper, which has been peer reviewed and assessed, we are now saying we have an organ in the body which hasn't been acknowledged as such to date," said J Calvin Coffey, a researcher from the University Hospital Limerick in Ireland, who first discovered that the mesentery was an organ.

"The anatomic description that had been laid down over 100 years of anatomy was incorrect. This organ is far from fragmented and complex. It is simply one continuous structure."

Thanks to the new research, as of last year, medical students started being taught that the mesentery is a distinct organ.

The world's best-known series of medical textbooks, Gray's Anatomy , has even been updated to include the new definition.

So what is the mesentery? It's a double fold of peritoneum - the lining of the abdominal cavity - that attaches our intestine to the wall of our abdomen, and keeps everything locked in place.

[...] Over the past four years, [researchers] gathered further evidence that the mesentery should actually be classified as its own distinct organ, and the latest paper makes it official. And while that doesn't change the structure that's been inside our bodies all along, with the reclassification comes a whole new field of medical science that could improve our health outcomes.

[...] It just goes to show that no matter how advanced science becomes, there's always more to learn and discover, even within our own bodies.

The research has been published in The Lancet Gastroenterology & Hepatology.