Which of the following CNS regions contains fenestrated capillaries that lack a blood-brain barrier, permitting circulating peptide hormones direct access to neurons?
- A Substantia nigra pars compacta
- B Dentate gyrus
- C Area postrema ✓
- D Caudate nucleus
Correct answer: C. Area postrema
Explanation
The area postrema, along with other circumventricular organs such as the OVLT, median eminence, pineal gland, subfornical organ, and posterior pituitary, has fenestrated, leaky capillaries without a blood-brain barrier. This allows blood-borne molecules including chemotherapeutic agents and angiotensin II to act there, explaining drug-induced vomiting from its chemoreceptor role. The other listed structures are deep parenchymal nuclei protected by a normal intact barrier.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.