Mesentery – The New Organ You Always Knew You Had

Written by Prabin Sharma  |  Department of Internal Medicine, Yale New Haven Health-Bridgeport Hospital

Coffey et al.¹ justify the designation of mesentery as an individual organ. Various news outlets have posted articles on this topic with sensational headings, but some of these articles are misleading, presenting Coffey’s findings in a different light than originally intended. For a layman, many of these headings suggest that scientists may have discovered a completely new organ hidden somewhere in the depths of the human body. This brief summary is aimed at showcasing the true findings of Coffey et al. in an accurate and representative manner.

What We Already Knew

The mesentery refers to a peritoneal fold lining the bowel containing two layers: the parietal and visceral peritoneum. Contiguity of the mesentery was suggested by various scientists at various point of time in our history, as early as Leonardo da Vinci. Culligan et al.² published the first study demonstrating the mesentery as a single unit in an observational study. There have been a few other studies supporting this finding but, in spite of these, the  mesentery has been presented as a fragmented structure and has been referred to by different names depending on the part of the gut it lines; Omentum when in conjunction with the stomach, the mesentery with the small intestine and the mesocolon with the large intestine. Other names such as mesoduodenum, mesoappendix, mesosigmoid, and mesorectum have also been used.

What Is New?

The mesentery, particularly the one associated with the small bowel and colon distal to the duodenojejunal flexure, is not a fragmented structure but a contiguous unit or organ. From the superior mesenteric root area, the mesentery spreads out over the intestine from the duodenum to the rectum. The continuity of the mesentery can only be demonstrated by peeling away the mesentery from the underlying fascia, in a similar fashion to the approach used in colorectal resection.

How Does This Affect The Scientific Community?

Coffey et al.¹ suggest that a better understanding of the mesenteric anatomy has helped in the derivation of universal surgical nomenclature, which is essential for systematic colorectal surgery. In addition, universal surgical nomenclature will further help standardise surgical procedure, including the resection method, and thus help validate comparison in clinical trials. The role of the mesentery in different disorders is postulated, including within diabetes, metabolic syndrome, obesity, inflammatory bowel disease, and colorectal cancer. Again, better understanding of the mesenteric anatomy will help scientists in further exploring its role in health and disease.

Further Research Is Needed

The anatomy of the mesentery proximal to the duodenojejunal flexure, such as the mesoesophagus and omentum, is not clear in terms of its contiguity. Multilevel and multisystem contiguity of the mesentery requires further studies to understand the spread of the disease from the mesentery to other body systems.

References

1. Coffey JC, O’Leary DP. The mesentery: structure, function, and role in disease. Lancet. Gastroenterol Hepatol. 2016;1(3):238-47.
2. Culligan K et al. The mesocolon: a prospective observational study. Colorectal Dis. 2012;14(4):421-8.