On H&E staining of a spinal cord anterior horn neuron, the cytoplasm shows large, granular, basophilic clumps. What is the primary ultrastructural composition of these Nissl bodies?
- A Rough endoplasmic reticulum and free ribosomes ✓
- B Smooth endoplasmic reticulum and mitochondria
- C Neurofilaments and microtubules
- D Lipofuscin granules and lysosomes
Correct answer: A. Rough endoplasmic reticulum and free ribosomes
Explanation
Nissl bodies are clusters of rough endoplasmic reticulum and free ribosomes, responsible for protein synthesis. Their basophilic staining on H&E is due to the high RNA content. Neurofilaments and microtubules form the cytoskeleton, while lipofuscin is a wear-and-tear pigment, neither of which forms the large basophilic Nissl granules.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.