Analysis Tools
mortality/aging
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• homozyogtes usually die between 35 and 40 days of age but a few survive for several months
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behavior/neurological
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• homozygotes assume a frog-like position with the hind legs abducted at the hips, flexed at the knees, and the metatarsus kept flat on the surface
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• waddling gait with the toes of the hind feet turned out, and unable to run normally but instead hop with inwardly rotated ankles or hocks, and with age the gait deteriorates so that they reel with the hind limbs and tail extended and frequently fall on their sides and exhibit periodic paraplegia
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• extremely excitable
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• periodic paraplegia with age
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nervous system
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• although neuroglia appear morphologically normal, they are smaller than normal and there are fewer of them
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• glial cell proliferation is found
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• all hindbrain structures are smaller than normal, with the cerebellum most severely affected, and both the white and grey matter of the medulla and cerebellum is reduced and the fiber tracts shortened
• the pontine neurons are smaller and less numerous than normal, the crossing fibers and nucleus of the trapezoid body are significantly reduced in size, the corticospinal tract and medial lemniscus are reduced in a sagittal plane
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• the medulla oblongata is shorter than normal
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• the pons is shorter than normal and has less grey and ventral white matter
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• the cerebellum is smaller than normal although the forebrain is of normal size
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• although normal in forebrain and midbrain, the neurons in the hindbrain and spinal cord are less numerous and smaller than normal, particularly in the trapezoid body, the pontine, olivary, and fastigial nuclei, and the spinal ganglia
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• loss of Purkinje cells occurs
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• the dorsal and ventral roots, spinal ganglia and nerves are severely reduced and smaller than normal
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• the spinal cord is thinner and shorter than normal, deficient in white and grey matter, with the funicular and short fiber tracts of the white matter smaller than normal and neurons, glia, glial fibers, and spinal ganglia in the grey matter smaller than normal
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• axonal dystrophy is consistently found in the spinocerebellar tract, lateral lemniscus, vestibulospinal and cerebellospinal tracts, in the medulla, in Purkinje cell axons as they traverse the granule cell layer, and in other fibers coursing adjacent to and between the neurons of the intracerebellar nuclei, with greatest severity in and around the fastigial nuclei
• axonal dystrophy is often severe in the dorsal and ventral root, cauda equina, and fibers of peripheral nerves
• characterized by coarse or bulbous bead-like thickenings and first detected at 16 days of age
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• myelin deficiency is severe in the lateral lemniscus and ventral spinocerebellar tract and is detected at 16 days of age
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growth/size/body
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• homozygotes are only half to three quarters of the size of normal controls
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muscle
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• the skeletal musculature is much reduced compared with controls
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skeleton
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• the vertebral column and spinal cord are undersized and thin, and the smaller size and underdevelopment of the vertebral column progresses caudad
• the vertebral bodies and spinous processs are shorter than normal, and the bony spicules and trabeculae are thinner and more delicate
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cellular
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• although neuroglia appear morphologically normal, they are smaller than normal and there are fewer of them
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• glial cell proliferation is found
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