Hirano bodies
Hirano bodies
1. Hirano bodies are primarily composed of:
A. Neurofilaments
B. Actin and actin-associated proteins
C. Tau protein
D. Ubiquitin
✅ Correct Answer: B
📘 Explanation: Hirano bodies are paracrystalline cytoplasmic inclusions composed primarily of actin and actin-associated proteins like tropomyosin.
2. Hirano bodies are most commonly found in which region of the brain?
A. Cerebellum
B. Substantia nigra
C. Hippocampus
D. Thalamus
✅ Correct Answer: C
📘 Explanation: Hirano bodies are frequently observed in the hippocampal neurons, especially in the CA1 region, in aging brains and Alzheimer’s disease.
3. Hirano bodies are commonly associated with which neurodegenerative disorder?
A. Parkinson’s disease
B. Huntington’s disease
C. Alzheimer’s disease
D. Multiple sclerosis
✅ Correct Answer: C
📘 Explanation: Hirano bodies are often found in Alzheimer’s disease and are considered one of the histopathological features along with amyloid plaques and neurofibrillary tangles.
4. The presence of Hirano bodies indicates:
A. Viral infection
B. Normal aging or Alzheimer’s disease
C. Acute ischemia
D. Genetic mutation in presenilin gene
✅ Correct Answer: B
📘 Explanation: Hirano bodies may appear in normal aging but are more frequently found in Alzheimer’s disease, suggesting cytoskeletal abnormalities.
5. What type of microscopy best visualizes Hirano bodies?
A. Brightfield microscopy
B. Transmission electron microscopy
C. Polarized light microscopy
D. Confocal laser microscopy
✅ Correct Answer: B
📘 Explanation: Electron microscopy reveals the paracrystalline, rod-like structure of Hirano bodies in neurons.
6. Hirano bodies are classified as which type of inclusion?
A. Intracellular nuclear
B. Extracellular
C. Cytoplasmic
D. Mitochondrial
✅ Correct Answer: C
📘 Explanation: Hirano bodies are cytoplasmic inclusions, found in neurons near the nucleus, usually in the hippocampus.
7. Which staining method can help visualize Hirano bodies under a light microscope?
A. Congo red
B. Hematoxylin and eosin (H\&E)
C. Periodic acid-Schiff (PAS)
D. Silver stain
✅ Correct Answer: C
📘 Explanation: Hirano bodies are PAS-positive, reflecting their glycoprotein content, and can also be seen with H\&E as eosinophilic inclusions.
8. What is the significance of Hirano bodies in aging?
A. They are pathognomonic for dementia
B. They are always pathological
C. They may occur in normal aging brains
D. They only appear in traumatic brain injury
✅ Correct Answer: C
📘 Explanation: Hirano bodies can appear in the brains of elderly individuals without clinical dementia, although they are more frequent in Alzheimer’s.
9. Which of the following best describes the appearance of Hirano bodies?
A. Spherical eosinophilic structures
B. Filamentous tau aggregates
C. Rod-shaped eosinophilic inclusions
D. Granular vacuolated lesions
✅ Correct Answer: C
📘 Explanation: Hirano bodies are typically described as rod-shaped eosinophilic cytoplasmic inclusions under light microscopy.
10. What cellular function is most disrupted by the formation of Hirano bodies?
A. Synaptic vesicle recycling
B. Mitochondrial respiration
C. Cytoskeletal organization
D. Lipid metabolism
✅ Correct Answer: C
📘 Explanation: Hirano bodies interfere with the cytoskeleton, particularly actin filament dynamics, affecting cellular transport and shape.
Hirano bodies
| No. | Feature | Description |
|---|
| 1 | Definition | Rod-shaped, eosinophilic cytoplasmic inclusions found in neurons. |
| 2 | Composition | Primarily composed of actin and actin-associated proteins. |
| 3 | Ultrastructure | Paracrystalline arrays of actin filaments observed under electron microscopy. |
| 4 | Location | Most commonly seen in the hippocampal neurons, especially CA1 region. |
| 5 | Staining | Eosinophilic with H&E; immunoreactive for actin, tau, and ubiquitin. |
| 6 | Associated Diseases | Commonly associated with Alzheimer’s disease and other neurodegenerative conditions. |
| 7 | Age Relation | Increased frequency with aging, even in neurologically normal elderly. |
| 8 | Significance | Thought to reflect cytoskeletal abnormalities and degeneration. |
| 9 | Actin Binding Proteins | Include cofilin, tropomyosin, and α-actinin. |
| 10 | Co-occurrence | Often found alongside neurofibrillary tangles in Alzheimer’s pathology. |
| 11 | Intracellular Location | Found in neuronal processes and soma, particularly in dendrites. |
| 12 | Discovery | First described by Asao Hirano in 1965. |
| 13 | Pathological Marker | Used as a histological marker of neuronal injury and aging. |
| 14 | Experimental Models | Induced in vitro in neuronal cultures under stress conditions. |
| 15 | Relation to Tau | Sometimes contain hyperphosphorylated tau protein. |
| 16 | Immunohistochemistry | Positive for actin, but also sometimes for heat shock proteins and ubiquitin. |
| 17 | Reversibility | Thought to be irreversible and associated with chronic pathology. |
| 18 | Cytoskeletal Disruption | Reflective of altered cytoskeletal dynamics in neurodegeneration. |
| 19 | Animal Studies | Found in aging non-human primates and some transgenic mouse models. |
| 20 | Clinical Implication | Not diagnostic alone but supportive in Alzheimer’s and other dementias. |
