Analysis Tools
mortality/aging
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• homozygotes die between 5 and 6 weeks of age
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behavior/neurological
opisthotonus
(
J:5025
)
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• at >30 days of age, homozygotes are unstable and walk stiffly
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• most homozygotes sink rapidly in water
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jerky movement
(
J:5025
)
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• homozygotes tend to lurch and launch forward
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• homozygotes maintain an upright sitting position with their tail and hindlimbs, flexing their forelimbs close to the chest
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• homozygotes eventually become paralyzed, are unable to stand and lay on their side with all limbs extended
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• homozygotes repeatedly run in "fits", attepmt to climb the walls and fall over, with feet continuing to pedal vigorously
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growth/size/body
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• at 30 days of age or later, homozygotes are about 50%-75% the size of control littermates
• all visceral organs appear normal but are uniformly smaller than normal
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• growth retardation is evident by 30 days of age
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nervous system
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• homozygotes display underdevelopment of certain brain regions
• however, no heterotopia is observed
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• several structures of the mutant hindbrain are significantly reduced in size
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• the mutant midbrain is smaller than that of control littermates
• in contrast, the overall size of the forebrain and its substructures is normal
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• the mutant medulla oblongata is smaller than that of controls and small relative to the size of the fore- and mibrain
• the volume of both white and grey matter is reduced
• medullary neurons are smaller than those of control littermates
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• the pons, trapezoid body, olivary and fastigial nuclei are significantly reduced in size
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• the mutant cerebellar cortex and most fiber tracts are reduced
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• Purkinje cells of the cerebellum are variably reduced in number
• shrunken Purkinje cells are observed
• basket remnants persist around some cells but are eventually lost
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• the mutant cerebellar granule cell layer is smaller than that of control littermates
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• the mutant cerebellum is slightly smaller than that of control littermates
• however, lobular formation and folia are normal
• the volume of both white and grey matter is reduced
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• some neuroglia are significantly reduced in number and size while others remain normal
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• the mutant pyramidal tract contains less fibers and is markedly smaller than that of control littermates and very small in proprtion to the medulla
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• in both spinal cord and medulla, afferent axons are swollen but less often than in efferent tracts
• in the medulla, axonal swellings appear as segmental or single coarse thickenings or bulbous-globular enlargements and occur primarily in efferent axons and most frequently in fibers of the tectospinal tract
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• mutant myelin sheaths are smaller and thinner than those of control littermates, resulting in white matter reduction
• however, no degeneration, total loss, or accumulation of myelin is observed
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• homozygotes show a disproportionate decrease in the size and number of neurons in the olivary and fastigial nuclei, spinal cord, and spinal ganglia
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• mutant spinal nerves appear smaller than normal
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• the mutant spinal cord is deficient in grey matter, with progressive severity caudally
• the funicular and short fiber tracts are smaller than normal
• neurons, glia and glial fibers of the grey matter, and spinal ganglia are smaller than normal
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• the mutant spinal cord is deficient in white matter, with progressive severity caudally
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• the mutant spinal cord is smaller and shorter than that of control littermates
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• a mild axonal dystrophy is observed in the cerebellum, probably involving both the Purkinje cells and granule cell axons
• a few axonal swellings and abnormalities are seen in the medial lemniscus and corticospinal tract caudad to brain stem as well as the dorsal spinocerebellar tract
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muscle
opisthotonus
(
J:5025
)
|
• homozygotes display a uniform muscle atrophy, affecting all fibers; muscles of the lower half of the body appear wasted
• fibers are closely packed within bundles
• centrally located nuclei and nuclear rowing are observed
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skeleton
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• the diameter of the vertebral column is smaller than normal, esp. at the lumbar level of the spinal cord
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• mutant spinous processes are shorter than normal
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• mutant trabeculae and bony spicules are thinner and more delicate than normal
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