In a longitudinal section of peripheral nerve, the endoneurium, perineurium, and epineurium are concentric sheaths. Which layer is formed by cells joined by tight junctions that create the blood-nerve barrier?
- A Endoneurium — fibroblasts loosely arranged
- B Epineurium — dense collagenous outer sheath
- C Perineurium — multilayered flattened cells with tight junctions ✓
- D Myelin sheath — Schwann cell membrane
Correct answer: C. Perineurium — multilayered flattened cells with tight junctions
Explanation
The perineurium forms the blood-nerve barrier. It consists of 7–15 concentric layers of flattened perineurial cells (modified fibroblasts) connected by tight junctions, gap junctions, and basal lamina. This barrier regulates the ionic microenvironment around nerve fibers and provides mechanical strength. The endoneurium is loose connective tissue around individual myelinated fibers with capillaries that also contribute to the barrier. The epineurium is the outer sheath of dense irregular connective tissue around the entire nerve. The myelin sheath provides saltatory conduction.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.