A type of mesothelial fibroblast that is derived from the neural crest, is localized on blood vessels, and is a key component of the pia and arachnoid membranes surrounding the brain. [ http://www.ncbi.nlm.nih.gov/pubmed/27284195 http://www.ncbi.nlm.nih.gov/pubmed/29443965 http://www.ncbi.nlm.nih.gov/pubmed/30096314 ]