Analysis Tools
mortality/aging
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• mutants appear to develop normally until the last fetal day but die in utero or are stillborn
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nervous system
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• although an intramuscular nerve trunk forms on time, axons that leave it extend parallel to the myotubes, branch infrequently, and are longer than controls by E15
• few of the axons that exit the main nerve trunk in E18 diaphragm muscles form secondary branches or arbors
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• synaptogenesis is impaired in superior cervical ganglion neuronal cultures, with mutants showing a decrease in the number of synapses with aggregates of presynaptic synaptophysin and postsynaptic neuronal acetylcholine receptor
• impaired synaptogenesis is not due to defects in neuronal differentiation or neurite outgrowth
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• presynaptic nerve differentiation and branching are abnormal
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• impaired postsynaptic differentiation, with a reduction in number, density, and size of postsynaptic acetylcholine receptor clusters on myotubes
• many axons terminate blindly, with no subjacent acetylcholine receptor aggregate and many acetylcholine receptor clusters are uninnervated
• the basal lamina of the synaptic cleft is frequently patchy instead of being continuous
• no junctional folds are seen at E18 synapses while controls have a few of these at this time
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• post-tetanic potentiation is greater in mutant superior cervical ganglion than in controls, indicating that synaptic transmission is defective
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• paired-pulse depression is more pronounced in mutant superior cervical ganglion than in controls
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