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Published on: June 15, 2018
Peripheral myelin in the mouse mutant Shiverer
Abstract:
The mouse mutant Shiverer has been shown previously to lack myelin basic protein and other myelin proteins in both the peripheral and central nervous systems. Examination by electron microscopy shows that the peripheral nervous system, in contrast to the markedly abnormal central nervous system, is grossly normal. Myelin sheaths are of the usual thickness and exhibit normal periodic structure consisting of alternating major dense and intermediate lines. Subtle abnormalities do occur, however, consisting of increased numbers of cytoplasm-containing lamellae, aberrant terminations of myelin lamellae in internodal regions, invagination of the axon by the inner tongue of the myelin sheath, myelin debris in both axon and Schwann cells, and disruption of outer myelin lamellae. Such changes have been seen previously in various types of neuropathy and are not pathognomonic of the Shiverer mutation. Despite the absence of myelin basic protein, the peripheral manifestations of this gene are relatively minor and probably not severe enough to compromise peripheral nerve function significantly.
Insights
The Shiverer mouse mutation causes severe central nervous system defects but only minor peripheral nervous system abnormalities. Despite lacking myelin basic protein, peripheral nerve function is likely unaffected.
Area of Science:
- Neuroscience
- Genetics
- Cell Biology
Background:
- The Shiverer mouse mutant lacks myelin basic protein (MBP) and other myelin proteins in the central and peripheral nervous systems.
- Previous studies indicate significant central nervous system (CNS) abnormalities in Shiverer mice.
Purpose of the Study:
- To investigate the structural integrity and functional implications of the peripheral nervous system (PNS) in Shiverer mice.
- To compare the PNS phenotype with the known severe CNS phenotype in Shiverer mutants.
Main Methods:
- Electron microscopy was used to examine the ultrastructure of the peripheral nervous system in Shiverer mice.
- Morphological analysis focused on myelin sheath thickness, periodic structure, and presence of abnormalities.
Main Results:
- The peripheral nervous system of Shiverer mice appeared grossly normal with usual myelin sheath thickness and periodic structure.
- Subtle abnormalities were observed, including increased cytoplasm-containing lamellae, aberrant myelin terminations, axonal invagination, myelin debris, and outer lamellar disruption.
- These subtle changes are consistent with general neuropathy and not specific to the Shiverer mutation.
Conclusions:
- Despite the absence of myelin basic protein, the peripheral nervous system in Shiverer mice exhibits relatively minor abnormalities.
- The observed peripheral nerve changes are unlikely to significantly impair peripheral nerve function.
