The Microbiota Is Not an Organ: Introducing the Muco-Microbiotic Layer as a Novel Morphofunctional Structure

In this paper, we want to refute the notion that the microbiota should be considered an organ, given that an organ comprises tissue of similar or different embryological origin, while the microbiota is a pool of different microbial species originating individually from single replications and not from a common ancestral cellular element. Hence, we would like to propose a new morphological interpretation of its nature, based on the comprehensive context in which these microbes live: a muco-microbiotic layer of hollow organs, such as the airways and the bowel. The above concept should represent not only a new terminological annotation but also a more accurate portrayal of the physiology and pathophysiology of these organs. Indeed, a better understanding of the biological nature of this part of the human body can help scientists develop more specific experimental protocols, potentially leading to the establishment of better therapeutic strategies.