Scientists have identified a new organ that has been hiding in plain sight inside the human body.

Previously Thought As A Fragmented Structure In The Digestive System

Known as the mesentery, the organ was previously thought to be a fragmented structure consisting of multiple separate parts in the digestive system. It is the double fold of the peritoneum, the lining of the abdominal cavity, and connects the intestine to the abdomen.

Leonardo Da Vinci Described The Organ As A Single Structure

For hundreds of years, the membrane was believed to consist of different structures. However, no other than Italian polymath Leonardo da Vinci identified the mesentery as a single structure in 1508.

Calvin Coffey, a researcher from the University Hospital Limerick in Ireland, and colleagues looked at earlier studies and literature on the mesentery and found that throughout the 20th century, anatomy books have described the structure as fragmented membranes. This means that different mesenteries were supposed to be associated with different parts of the intestines.

New Studies Show Mesentery Is One Continuous Organ

Now, they found evidence that back up one of the earliest descriptions of the membrane: the mesentery is one structure and deserves to be recognized as one continuous organ.

Based on observations of the structure in cadavers and patients who underwent colorectal surgery, Coffey and colleagues concluded that the membrane is a continuous organ.

Coffey and colleagues outlined the evidence to support categorizing the mesentery as an organ in a review published in The Lancet Gastroenterology & Hepatology.

"Distinctive anatomical and functional features have been revealed that justify designation of the mesentery as an organ," Coffey and colleagues wrote. "Accordingly, the mesentery should be subjected to the same investigatory focus that is applied to other organs and systems."

Function Of Mesentery Not Yet Clear

The function of the mesentery is still unclear but Coffey said that its discovery opens up a whole new area of science. Researchers have also yet to identify what particular body system the mesentery should be classified in.

"Whether the mesentery should be viewed as part of the intestinal, vascular, endocrine, cardiovascular or immunological systems is so far unclear, as it has important roles in all of them," the researchers wrote.

Significance Of Recognizing The Mesentery As An Organ

Coffey said that if the mesentery is approached like every other organ, abdominal diseases can be categorized in terms of this organ.

The researchers said that having a better understanding and further scientific study of the organ may pave the way to less invasive surgeries, fewer complications, and faster recovery of patients that can eventually lower overall costs.

"We have established anatomy and the structure. The next step is the function," Coffey said. "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."

The research has prompted an update in one of the best known medical textbooks worldwide, Gray's Anatomy. Medical students are now learning about the mesentery as a continuous organ.

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