Our findings of claudin-11 in the arachnoid blood-CSF barrier and EAAT1 and IL-13Rα2 in the outer CSF-brain barrier confirm their barrier properties and the spatiotemporal distribution of YKL-40/BLBP/SSEA-4 further establish the necessity of regarding these interfaces as separate entities, since they may play different roles in normal brain development and possibly in several neurological disorders. This evidence concerns the gene CHI3L1 and nervous system disorder.