Podcast
Questions and Answers
What occurs during retrograde degeneration of a nerve fiber?
What occurs during retrograde degeneration of a nerve fiber?
Which change is NOT associated with Wallerian degeneration?
Which change is NOT associated with Wallerian degeneration?
What role do macrophages play in nerve regeneration?
What role do macrophages play in nerve regeneration?
Which type of astrocyte is characterized by many short processes and is located in grey matter?
Which type of astrocyte is characterized by many short processes and is located in grey matter?
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What is the primary function of astrocytes in the nervous system?
What is the primary function of astrocytes in the nervous system?
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What process occurs in the distal part of a damaged nerve fiber during Wallerian degeneration?
What process occurs in the distal part of a damaged nerve fiber during Wallerian degeneration?
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Which of the following best describes the 'fermentation chambers' in nerve tissue?
Which of the following best describes the 'fermentation chambers' in nerve tissue?
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What staining technique is used to demonstrate changes in the Nissl bodies during degeneration?
What staining technique is used to demonstrate changes in the Nissl bodies during degeneration?
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Study Notes
Nerve Degeneration and Regeneration
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Retrograde degeneration occurs in the nerve cell and proximal part of the nerve fiber.
- Chromatolysis: Disappearance of Nissl bodies, decrease in basophilia, increase in perikaryon volume, loss of dendrites, migration of nucleus to periphery, Golgi body and mitochondria disappearance, neurofibril fragmentation, and lysosome increase.
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Wallerian degeneration occurs in the distal part of the nerve fiber.
- Axon: Neurofibrils become beaded, segmented, granular, and finally disappear.
- Myelin sheath: Widening of nodes of Ranvier, internodal segments become "fermentation chambers."
- Schwann cells: Proliferate, forming cellular columns that guide growing axons during regeneration.
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Stains used for degeneration:
- Silver: Demonstrates changes in Golgi body and neurofibrils.
- Osmic acid: Demonstrates changes in the myelin sheath.
- Basic stains: Demonstrates changes in Nissl bodies.
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Regeneration of nerve fibers:
- Macrophages: Remove debris and secrete interleukin-1, stimulating Schwann cells to secrete nerve growth-promoting substances.
- Growth of axons: Occurs in the proximal part in the direction of Schwann cell columns.
- Efficient regeneration requires proper alignment of fibers and Schwann cell columns.
Central Neuroglia
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Astrocytes:
- Cytoplasmic astrocytes: Found in gray matter, granular cytoplasm, many short processes.
- Fibrous astrocytes: Found in white matter, fibrous cytoplasm, many long processes.
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Satellite cells:
- Found in gray matter, closely associated with neuron cell bodies.
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Interfascicular:
- Found in white matter, between bundles of axons.
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Functions of astrocytes:
- Metabolic exchange control: Processes with expanded end feet linked to blood capillary endothelium regulate exchange.
- Blood brain barrier:
- Structural support:
- Repair process: Formation of scar tissue.
Peripheral Neuroglia
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Schwann cells:
- Found in the peripheral nervous system, responsible for myelin production, electrical insulation, and regeneration.
- Origin: Ectodermal.
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Satellite cells:
- Low cuboidal cells found in the peripheral nervous system.
- Location: Surround nerve cells in ganglia.
Ependymal Cells
- Location: Line the central canal of the spinal cord and ventricles of the brain.
- Structure: Form a simple cuboidal or columnar epithelium, may be ciliated.
- Function: Cilia may be involved in cerebrospinal fluid (CSF) propulsion.
- Origin: Ectodermal.
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Description
This quiz explores the mechanisms of nerve degeneration and regeneration, focusing on retrograde and Wallerian degeneration. Key concepts such as chromatolysis, axonal changes, and the role of Schwann cells in healing are covered, alongside the staining techniques used to visualize these processes.
