Involvement of claudins in zebrafish brain ventricle morphogenesis

Zebrafish brain ventricle morphogenesis involves an initial circulation-independent opening followed by a blood flow- and circulation-dependent expansion process. Zebrafish claudin-5a is required for the establishment of a neuroepithelial-ventricular barrier, which maintains the hydrostatic pressure within the ventricular cavity, thereby contributing to brain ventricle opening and expansion. In mammalia, several claudin family members, including claudin-3 and claudin-5, are expressed within microvessel endothelial cells of the blood-brain barrier. Whether zebrafish brain ventricle morphogenesis provides a model for studying these claudins during early embryonic development was unknown. This review focuses on the expression and function of these zebrafish claudins during brain ventricle morphogenesis.