The fourth VLMC-like cell type (enteric mesothelial fibroblasts; ENMFBs) expressed all the VLMC marker genes but was found exclusively in the enteric nervous system. This demonstrates that VLMC-like cells are present throughout the body and are not brain specific. Like the brain, organs of the abdomen are wrapped in protective layers of cells, which serve protective, lubricating, and active signaling functions, especially during development. Our observations thus support the view that VLMC-like cells are a family of functionally related (but organ-specific) mesothelial fibroblasts that form protective membranes around internal organs, including the pia and arachnoid membranes of the brain. The fact that ENMFBs were obtained by sorting Wnt1-Cre;R26Tomato cells indicates that these cells are derived from the neural crest, as has previously been shown for both pia and arachnoid.
