A team of researchers from the University Hospital Limerick in Ireland has discovered a new organ that has been hiding inside the human body the whole time. Known as the mesentery, the newly identified organ is a double fold of peritoneum that connects the abdomen to the intestine. According to J Calvin Coffey, the lead researcher of the study, the function of this newly discovered organ is clearly not understood, but he believes their discovery has open up “a whole new area of science.”

“When we approach it like every other organ… we can categorize abdominal disease in terms of this organ,” says Coffey in a news release. “Now we have established anatomy and the structure. The next step is the function. If you understand the function you can identify abnormal function, and then you have disease. Put them all together and you have the field of mesenteric science.”

Shown below is the digital representation of the mesentery and small and large intestines:

The mesentery was, in fact, described by Italian polymath Leonardo da Vinci in the year 1508, but researchers have long thought it to be a series of fragmented structures in the digestive system, and therefore it’s not an organ, the Independent reports. However, new examinations of it on a microscopic level has now proven that it is in fact one, continuous organ.

The team is working on figured out how exactly the mesentery works, and they believe once they do so, it could ultimately lead to better treatment for digestive and abdominal diseases. The study has been published in The Lancet Gastroenterology & Hepatology.

[Image : J Calvin Coffey, D Peter O’Leary, Henry Vandyke Carter]