“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.

One of the earliest descriptions of the mesentery was made by Leonardo da Vinci, and for centuries it was generally ignored as a type of insignificant attachment. Over the past century, doctors who studied the mesentery assumed it was a fragmented structure made of separate sections, which made it pretty unimportant.

But in 2012, Coffey and his colleagues showed through detailed microscopic examinations that the mesentery is actually a continuous structure.”