Many of our organs, such as the heart or the lungs, are coated with a thin membrane called the mesothelium, lined with immune cells helping to protect them. Kjeld Mollgard, professor of neuroanatomy at the University of Copenhagen, wondered if such a structure did not surround our brain. Associated with researchers from the University of Rochester (United States), the Dane describes in Science from January 6 such an envelope, observed both in mice and in humans. Made of a tiling only a few cells thick, it had escaped neuroscientists, who had described only three meningeal barriers. The newcomer appears to be involved in circulating cerebrospinal fluid and watching for signs of infection or inflammation. An entire chapter of anatomy textbooks to revise!
