Our Old Friend, The Mesentery

In the wake of our recovery from the bewildering circumstances of 2016, many of us awoke in the early January mornings to some astonishing medical news. News sites everywhere were reporting that a new human organ had been discovered: the mesentery. Yet some of the article headlines made it seem like the pesky little organ had been hiding away undetected until one fateful morning where we all suddenly woke up with a brand new organ, fresh from the stem cells below.

The reality is, we’ve known about the mesentery for quite some time, dating all the way back to Leonardo Da Vinci himself. Our mesentery has always been there. Watching. Waiting. With every move we make. With every breath we take. …Well, perhaps not so ominously.

What is the mesentery?

Simply put, the mesentery is a set of tissues that attaches and secures our intestines to the wall of our abdomen1. More specifically, the mesentery is the double fold in the lining of our abdominal cavity, more formally known as the peritoneum, and it is this fold that forms an attachment between the two parts of the body.

A figure from the recently published paper digitally depicts the mesentery with respect to the small and large intestines. (Coffey & O'Leary, 2016)
A figure from the recently published paper digitally depicts the mesentery with respect to the small and large intestines. (Coffey & O’Leary, 2016)

The earliest records we have of this anatomical structure dates back to Leonardo da Vinci’s research, where he noted the continuous structure of a set of tissues associated with the small bowel and colon1. Further medical research reached varying conclusions over whether these tissues were indeed continuous or not, but a recent scientific article published by scientists from the University Hospital Limerick in Ireland delineates the evidence for the continuity of the mesentery, as well as the classification that accompanies such a feature. The authors and scientists, J Calvin Coffey and D Peter O’Leary, claim that the mesentery’s continuity, among other anatomical characteristics, deems it worthy of a reclassification as an organ instead of just a collection of tissues. The change in title is not a mere battle of semantics, however, as the differences between an organ and a tissue lead to different approaches, understandings, and perspectives in biology and medicine. All in all, the scientists claim that the reclassification could ultimately support more targeted research and education pertaining to the mesentery and its related structures, allowing for better medical treatment and greater scientific understanding.

What is the difference between an organ and a tissue?

The mesentery had previously been considered a set of tissues; that is, a group of cells that are typically of the same variety (e.g. epithelial tissue or neural tissue) that work and communicate together. Its continuous and contained nature, however, are part of what led Coffey and O’Leary to propose its reclassification as an organ. Generally speaking, an organ is defined as a group of tissues that are connected, self-contained, and perform a specific function3. General scientific research found the associated lymphatic, neurological, vascular, and connective tissues to be continuous throughout, thereby suggesting that the mesentery indeed appears to be a connected and perhaps central organ structure after all1. Its classification into an organ system, however, remains unclear, and the authors suggest that it could very well play a key role in multiple organ systems. With this new classification also comes the challenge of identifying the functional unit of the mesentery, if one does exist, and if there is a particular cell type that is largely responsible for the mesentery’s overall function1.

How does this reclassification change things?

Coffey and O’Leary suggest that a better categorization of the mesentery could allow for better research and medical practices involving it and any associated structures. The continued development of better mesentery diagnostics, through radiology and endoscopy, could better identify the stages of abdominal diseases through minimal to non-invasive methods1. Such diagnostic methods could also lead to better medical research into the mesentery, which could benefit pharmacological advancements that may obviate the need for surgical intervention or at the very least, could grant us a better understanding of how drugs interact with the mesentery. Ultimately, the team of researchers claim that this reclassification has set the precedent for an entirely new field of science, just waiting to be…fleshed out.

“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. Put them all together and you have the field of mesenteric science…the basis for a whole new area of science,” he [Coffey] said2.


  1. Coffey, J. C., & O’Leary, D. P. (2016). The mesentery: structure, function, and role in disease. The Lancet Gastroenterology & Hepatology, 1(3), 238-247.
  2. [Press Release] “Irish surgeon identifies emerging area of medical science” (2016). University of Limerick Wesbite.
  3. Foundational Model of Anatomy Database. Structural Informatics Group, University of Washington. http://xiphoid.biostr.washington.edu/fma/fmabrowser-hierarchy.html?fmaid=67498

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