The Mesentery: The Human Body’s 79th Organ?

By Nathaniel Scharping | January 3, 2017 2:23 pm
turns-out-the-mesentery-is-one-continuous-organ

(Credit: J Calvin Coffey/D Peter O’Leary/Henry Vandyke Carter)

Editor’s note: For a deeper exploration of the mesentery — including if it should actually be called “our 79th organ” — click here.

To the 78 organs that make up the human body, a group of scientists says we should add one more: the mesentery.

Located in our abdominal cavity, the mesentery is a belt of tissue that holds our intestines in place. While anatomists knew it was there, it was always thought to be composed of several different segments, as opposed to being one single structure. This knocked it out of contention for organ status, as our bodily organs must be continuous, as well as provide some vital function to our anatomy.

A new study from researchers at the University Hospital Limerick reveals that the mesentery is actually one single band of tissue, beginning at the pancreas and continuing down through the small intestine and colon, wrapping around these vital organs to hold them tight and help them maintain their structure. It is made of a folded-over ribbon of peritoneum, a type of tissue usually found lining the abdominal cavity.

“Without it you can’t live,” says J. Calvin Coffey, a Limerick University Hospital researcher and colorectal surgeon. “There are no reported instances of a Homo sapien living without a mesentery.”

It was by peeling away the peritoneum and repeated observations that Coffey built his case for the mesentery. In 2012, Coffey’s team determined the mesentery was indeed a single, connected structure. In this most recent study, published in The Lancet, Coffey’s team outlines evidence collected over four years that it says affirms the mesentery’s organ status. The mesentery is highly integrated with the intestine, he says, and is located in an area of the human body that has not been fully explored — we still, apparently, contain new frontiers.

And, according to The Independent, the seminal medical textbook Gray’s Anatomy was updated in 2015 to include the new definition of the mesentery. However, Coffey isn’t exactly sure when an organ is officially an organ.

“That’s a fascinating question. I actually don’t know who the final arbiter of that is,” says Coffey.

In apes and other creatures that walk on all fours, he says that the structure of the mesentery, and the organs it supports, is slightly different, which affects the layout of their guts. 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 disease that we are stalled on, and we need to refresh our approach to these diseases,” Coffey says. “Now that we’ve clarified its structure, we can systematically examine it. We’re at a very exciting place right now.”

The era of mesenteric science has taken a new turn.

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  • Andy Anderson

    It’s intriguing how much we have yet to understand and discover the human body thus far. The discovery not only shows the importance of and how vital the mesentery is to our bodies but the discovery of this new organ. It really shows that something that seems like nothing can hold a great importance, especially since we are learning that we cannot live without it. Learning and validating the function of the mesentery will really make a statement that it is an organ and not just a ribbon of skin around the pancreas through the intestines. It raises the question of what is the function and why does it carry such an importance.

    • Jerry A

      This is just a guess, but think about what would happen in the digestive tract without a supporting structure. Soon after a meal, the weight of food in the stomach and upper part of the intestine would push down on the folds of intestine below it, perhaps limiting muscular contractions or even causing folds and blockages. Later on, digested food moving through the large intestine might cause the same problems to the small intestine below it. A large enough meal might push down one section of the intestine to the bottom of the abdomen, maybe staying down there and not moving onwards. (That sure does not sound good to me.) Saying that a person would not survive without a mesentery organ does not sound all that far-fetched, even though it was not at the top of my list of essential body parts before today. (I’d barely even heard of it before.)

  • Daphne Macklin

    And just when we thought we had it all figured out in the gross anatomy department and had gone all genomic. Nice catch!!!

  • arch 1

    Another example of the multiple paradoxes in life. The more we learn the more we find there is much we do not know. We are finding new things about the human organism in toto but have yet to really understand our uniqueness as individuals. We are all unique,,, just like everyone else..

  • Hernan Diaz

    Compare mesentery and skin

  • Tom

    “It is made of a folded-over ribbon of peritoneum,…” how is this then differentiated from the greater and lesser omentum which, likewise are folded layers of peritoneum?

    • https://www.facebook.com/pages/My-Original-Music-written-arranged-produced-by-ME/195887277117017 JohnnyMorales

      The omentum is part of the peritoneum, but not all of it, and if you accept the definition that the peritoneum is an organ unto itself, it is not valid to describe the omentum as you did.

  • Robert Cohen

    This organ would be damaged in gastric bypass surgery. Does this contribute to the long term complications of this operation?

    • indy483rdFMS

      Why are you asking me?

      • http://Private.individual.org/ Heimdall222

        Because you look like a mesentery. Ummm, no, that’s…anus!

  • StevenRobert

    I don’t see how it is not an integral part of the intestinal tract, and how making it a separate “organ” is helpful in understanding anatomy and physiology.
    The mesentery is essential for the intestines to complete their function and probably neither could function independently.

    There are the “lumpers” and the “spliters” in naming, terminology and physiology. This is similar to the nomenclature of new species, sometimes separating species and even genera. In scientific nomenclature, sometimes “subspecies” is a more appropriate term, since species are sometimes difficult to separate, but usually it indicates an ability to procreate within a species with fertile offspring, although even this doesn’t always clearly define a species or subspecies, modern genetic mapping sometimes being resorted to in defining a separate species.

    I would be more in favor of referring to the mesentery in it’s more traditional understanding as a supporting element and integral aspect of that portion of the digestive system it is contained with such as pancreatic, small or large intestinal mesentery. This would facilitate understanding of the integral aspects of the human body, or any body for that matter working as an integrated whole rather than trying to separate it into separate aspects.

    Medicine has already reached a point of specialization and subspecialization to the point that training and fellowships are already concentrated on increasingly isolated aspects of anatomy, such as liver and pancreatic, and intestinal specialization in GI and cardiovascular or heart and vascular system. Dermatology, the eye with retinal surgeons vs specialization in cataract extraction. This is helpful to a certain degree, but is reaching the point where subspecialization in individual organs limits understanding of the way the body integrates functions and may also limit researchers attempting to understand bodily function.

    • Maliwan Eryigit

      interesting need to prove

      • StevenRobert

        Thanks for the response. With respect to proving that the mesentery is not an organ, perhaps for detailed understanding of its function, it could be considered and organ, however in the traditional study of anatomy, it would be considered part of the omentum, and integral or inter-related to the intestines. The intestines certainly would not have any function at all without the omentum and probably would not survive as separate organs.

        In the understanding of obesity, diabetes, even anorexia, omental/intestinal relationships need to be better understood. The surprising effect of some kinds of intestinal bypass surgery, essentially curing type 2 diabetes is still not understood that I am aware of, and considering the widespread development of type 2 diabetes, it really needs to be better understood as a public health issue.

        Certainly the mesentery and omentum deserve close attention, and if considering the mesentery as a separate organ facilitates such studies, then it probably is worth while, but for the ordinary physician or anatomist, probably considering them as an integral functioning unit in their traditional understanding is still the best approach.

  • M.R Srinivasan

    Whether the mesentery is deemed as a separate organ as perceived now or just an integral part of the intestinal tract as of old thinking, its intended purpose as one or more vertebrate membranes comprising a double fold of the peritoneum connecting the intestines and their appendages with the dorsal wall of the abdominal cavity, is not going to change but for indefinable evolutionary changes in the future !
    Any research into their functionality now on can only be illustrative more of its as yet not thoroughly understood assisting factors that make the intestines function as they have been intended to.

  • Cherryl

    So, the researchers are saying that if we can live without certain tissue, then it is not an organ? I’m not sure how they arrived at the conclusion that no human can live without a mesentery, since removing it would involve a long, drawn out operation. I hope they didn’t test out the theory.

    The good news seems to be that surgeons may start treating all the tissues in the body more carefully as they attack the parts they intend on flaying at the moment.

  • SuHil

    I find this article one more of so many that are so interesting it needs to be read over and over. Thank you for sharing information on one more of God’s interesting creations.

  • George Pope

    To me, an “organ” is a unique organelle made up of cells unique to it.

    Otherwise, how is this an organ, deemed separate from the rest of the peritoneum?

  • Human Anatomy UoN

    Is it that anatomists are eager to split everything up, new organs, new structures, for descriptive sake, without necessarily adding new value?

  • Richik Nandy Majumder

    Sir, almost all peritoneal folds are continuous. If mesentery is considered to be an organ then why not the omenta?
    Plz throw some light over my confusion.

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