Answer
The brain cerebrospinal fluid barrier (BCFB) is formed by the tight junctions of ependymal cells.
The blood brain barrier (BBB), is formed by the tight junctions of brain capillary epithelial cells reinforced by the endothelial basement membrane, ependymal cells and astroglial secretions
Work Step by Step
Ependymal cells cover choroid capillaries. Fluid is filtered from capillary blood and secreted by ependymal cells to produce CSF. Because of the tight junctions between the ependymal cells, substances that enter the CSF from the choroid capillaries, cannot leak back between the ependymal cells; instead they must pass through the ependymal cells . This enables the ependymal layer to select which substances to admit and which to exclude.
