Does Intestine Morphology Still Have Secrets to Reveal? A Proposal about the “Ghost” Layer of the Bowel

In this brief Opinion paper, the term “muco-microbiotic layer” is introduced to describe the innermost layer of the intestinal wall. This layer may contribute not only to the overall health of the bowel, but also to that of extraintestinal organs. Its constituents, in terms of soluble molecules and nanovesicles, need to be studied further. Moreover, one can hypothesize the existence of an analogous layer in other organs, such as the airways or some parts of the genital tracts. Further studies on it are needed.