Scientists Officially Classify New Organ in Human Bodies

Your body has one more organ than previously thought, according to new research from Ireland’s University Hospital Limerick. The new organ is called the mesentery, an object that was formerly believed to be several tissue structures. Researchers have called this a major breakthrough in the fields of abdominal and digestive diseases.

A new paper published in the Lancet Gastroenterology & Hepatology has reclassified the mesentery, formerly thought to be a fragmented membrane, as an organ, following microscopic research that revealed it to be one continuous structure. The mesentery is a double fold of peritoneum (the membrane that forms the lining of the abdomen) that attaches the gastrointestinal tract to the walls of the abdomen. Nerves and blood vessels are sandwiched in the fold.

Leonardo Da Vinci identified the mesentery as an organ over 500 years ago, but the medical community rejected his claim. In 1885, Sir Frederick Treves, the royal surgeon to Queen Victoria and King Edward VII, described it visually as several unconnected structures with complex interactions. The royal surgeon's definition "was indoctrinated into mainstream surgical, anatomical, and embryological literature over the past century," according to a 2014 paper coauthored by Limerick senior researcher J. Calvin Coffey. 

In 2012, Coffey's team conducted a detailed microscopic examination of the mesentery that revealed the tissue arrangement to be a continuous structure, indicating that it is an organ. Coffey wrote that "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."

After four additional years of research, Coffey published his case for reclassifying the organ, hoping that his team's discovery can lend itself to advances in abdominal medicine. "When we approach it like every other organ… we can categorise abdominal disease in terms of this organ," he said. Coffey also called the discovery "the basis for a whole new area of science."

"This is relevant universally, as it affects all of us. Up to now there was no such field as mesenteric science. 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," said Coffey.

Grey's Anatomy, one of the most influential and significant medical textbooks, agrees with Coffey's assertion, changing its description of the mesentery to an organ in its most recent edition.