Are there 78 or 79 organs?

The question of whether there are 78 or 79 organs stems from recent debate over whether the mesentery (tissue connecting the intestine to the abdominal wall) qualifies as a distinct organ. However, organ counts vary depending on classification criteria, and there's no universally agreed number.

The mesentery controversy arose when researchers proposed in 2017 that this connective tissue structure should be classified as an organ due to its continuous structure and distinct functions beyond simply anchoring the intestines. This proposal would change the organ count from 78 to 79. However, anatomists and medical professionals debate organ definitions and counts. Some lists include 78-80 organs, while others count differently based on criteria for organ designation. The ambiguity stems from definitional questions: Are paired organs (two kidneys, two lungs) counted individually or as single organ systems? Are the teeth considered organs? What about individual bones—are they organs? Different authorities answer these questions differently. Ultimately, the specific number matters less than understanding that organs are structures composed of multiple tissue types working together to perform specific functions. The human body contains major vital organs (heart, brain, lungs, liver, kidneys) essential for survival, as well as numerous other organs supporting various functions. The mesentery, regardless of "organ" classification, plays important roles in intestinal function, immune response, and possibly disease development. Rather than focusing on exact counts, medical education emphasizes understanding each structure's function, relationships with other body parts, and clinical significance. This functional understanding proves more valuable than memorizing arbitrary organ numbers, which may shift as anatomical knowledge and classification systems evolve.