While it may never achieve the rock star status that the heart, liver or lungs enjoy, the mesentery was officially given full organ status in 2017, bringing the total number of organs in the human body to 79. Not familiar with it? Well, the mesentery is a band of tissues in the digestive system that begins at the pancreas and continues through the small intestine and colon, holding these organs in place.
The process for status upgrade to organ began in 2012 when researchers from the University of Limerick in Ireland determined the mesentery is self-contained. Before that, it was widely accepted that the mesentery was composed of multiple attached pieces, rather than functioning as a continuous organ.
Besides self-containment, there's one other bit of criteria to being named an organ — it must perform a critical function. From the get-go, scientists knew that the mesentery kept the gut in place by attaching it to the abdominal wall, which in and of itself is pretty important. "There are no reported instances of a Homo sapien living without a mesentery," researcher and University of Limerick professor J. Calvin Coffey told Discover magazine in 2017.
The mesentery is also where all abdominal organs develop. If this doesn't happen properly during fetal development, all kinds of things can go wrong. For instance, intestines may twist or collapse, which can cause tissue death or blocked blood vessels.
Lymph nodes are also located in the mesentery, and that's important because these nodes help the body fight off infections as they contain immune cells and also trap viruses, bacteria, etc.
Lastly, the mesentery, when needed, can produce C-reactive protein. This protein is a warning shot of sorts that the body is experiencing inflammation.
In 2021, scientists published a study in Nature confirming that there is only one mesentery in the body to which all abdominal digestive organs are connected and that across animal species, abdominopelvic organs (stomach, liver, intestines, etc.) are organized into mesenteric and non-mesenteric domains.
The mesentery discovery even prompted an update to the medical textbook "Gray's Anatomy." Not too shabby for a heretofore largely overlooked body part.