The blood-brain barrier and the blood-cerebrospinal fluid barrier differ anatomically. In the choroid plexus, the site of tight junctions forming the blood-CSF barrier is:
- A Between the fenestrated capillary endothelial cells
- B Between the ependymal cells lining the ventricular surface
- C Between the cuboidal epithelial cells on the ventricular surface of the plexus ✓
- D Between astrocyte foot processes surrounding the capillaries
Correct answer: C. Between the cuboidal epithelial cells on the ventricular surface of the plexus
Explanation
Choroid plexus capillaries are unusually leaky and fenestrated, so the selective barrier there is provided instead by tight junctions between the choroid epithelial cells that face the ventricle. This contrasts with the cerebral cortex, where the barrier sits at the nonfenestrated endothelium itself. Ependymal lining elsewhere is loosely joined to allow exchange between CSF and brain interstitium, which is why tracer studies show free diffusion across the ventricular wall.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.