Which structure forms CSF by filtering plasma?

Which structure forms CSF by filtering plasma?

• A. Choroid plexus
• B. Arachnoid granulations
• C. Dural sinuses
• D. Ependymal cells

Answer: (A)

CSF is produced inside the brain by the choroid plexus, a network of capillaries within the ventricles surrounded by specialized ependymal cells. Plasma filters through these capillaries and is actively secreted and modified by the choroid plexus epithelium to form cerebrospinal fluid, which has a clear, low-protein composition suitable for cushioning and nourishing the brain. Arachnoid granulations are involved in returning CSF to the bloodstream, dural sinuses are venous channels draining blood, and while ependymal cells line the ventricles and help circulate CSF, the primary site of CSF formation from plasma is the choroid plexus.

CSF is produced inside the brain by the choroid plexus, a network of capillaries within the ventricles surrounded by specialized ependymal cells. Plasma filters through these capillaries and is actively secreted and modified by the choroid plexus epithelium to form cerebrospinal fluid, which has a clear, low-protein composition suitable for cushioning and nourishing the brain. Arachnoid granulations are involved in returning CSF to the bloodstream, dural sinuses are venous channels draining blood, and while ependymal cells line the ventricles and help circulate CSF, the primary site of CSF formation from plasma is the choroid plexus.