This new organ called the mesentery is a fatty membrane that holds the intestines in place, so rather than being comprised of a series of individual, fragmented structures that adhered the intestines to the abdominal wall, the mesentery is a single structure, wrapping and folding around in one long, continuous piece of tissue. What was once previously thought to be just a few fragmented structures in the digestive system is, in fact, one continuous organ. It begins at the pancreas and wraps around the small intestine and colon, and serves the purpose of holding these organs in position so they can perform their respective functions.
“Without it you can’t live,” lead researcher Dr. J. Calvin Coffey, a colorectal surgeon at Limerick, told The Lancet Gastroenterology & Hepatology: “There are no reported instances of a Homo sapien living without a mesentery.”
Although there are generally considered to be five organs in the human body, there are in fact now 79, including the mesentery, and while its specific function is still unknown, studying it as an organ could lead to new discoveries about its impact on abdominal diseases, and may regulate the migration of white blood cells throughout the intestines. Coffey added:
“Understanding how and why our digestive system is arranged the way it is could be crucial to our understanding of diseases like Crohn’s and irritable bowel syndrome…There are a lot of diseases that we are stalled on, and we need to refresh our approach to these diseases…Now that we’ve clarified its [the mesentery’s] structure, we can systematically examine it. We’re at a very exciting place right now.”
Back in 2012, Coffey and his colleagues showed through detailed microscopic examinations that the mesentery is actually a continuous structure. Over the past four years, they’ve gathered further evidence that the mesentery should actually be classified as its own distinct organ, and the latest paper makes it official.
Gray’s Anatomy, the world’s most famous medical textbook, has been updated to include the new definition.
Images: The Lancet Gastroenterology & Hepatology