Analysis Tools
mortality/aging
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• homozygotes with severe forelimb abnormalities often die within 2 to 3 days after birth due to difficulties in positioning themselves for suckling and thus do not get enough nourishment, however if they do survive the first few weeks, their condition usually begins to improve and some have a relatively normal lifespan
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growth/size/body
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• adults with forelimb abnormalities are almost always smaller than controls
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nervous system
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• exhibit a variable increase in peripheral nerve fasciculation and an occasional mild increase in endoneural connective tissue, however no differences in the number of Schwann cells or any evidence of denervation atrophy
(J:11392)
• all peripheral nerves are hypotrophic
(J:105260)
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• the axons that are enclosed by promyelin fibers have smaller axon calibers than those of myelinated fibers
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• variable degree of generalized hypomyelination, with peripheral myelin sheaths thinner relative to axonal size than in controls
(J:11392)
• in some mutants, the ratio of myelin sheath thickness to axon caliber is reduced
(J:24743)
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• hypertrophy of the sciatic nerve
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• all homozygotes have delayed and abnormal myelination of the peripheral nervous system but not the central nervous system
(J:11392)
• failure of myelination in some fibers leads to persistent promyelin fibers with small axons, especially in muscles that normally have small axons
(J:11392)
• delay in myelination and a persistence of some axons and Schwann cells in the promyelin configuration throughout life
(J:24743)
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limbs/digits/tail
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• abnormally flexed joints can be extended early in life but fixed contractures often develop with age
(J:11392)
• exhibit an arthrogryposis-like phenotype affecting the forelimbs, and in severe cases, also the hindlimbs
(J:105260)
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• fingers are flexed
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• forelimbs with abnormal postures are held flexed at one or more of the shoulder, wrist or digital joints but extended at the elbow, resulting in the forelimbs being pointed toward the hindlimbs
(J:11392)
• flexed forelimbs (fingers, wrists, shoulders), elbows rotated inwards
(J:24743)
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• radii are thinner and somewhat straighter than in controls, however gross bony landmarks and sections through bones and joints appear normal
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• ulnae are thinner and somewhat straighter than in controls
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• hindlimbs are more subtly affected than forelimbs, with the most common abnormality a mild, usually symmetrical, weakness of hindpaw dorsiflexion
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behavior/neurological
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• unable to extend an affected forelimb above the head as part of a righting response when turned from its back onto one side
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• abnormal forelimb joint postures seen within 1-2 days after birth
(J:11392)
• postural deformity (waiter's tip posture) of one or both forelimbs in which the fingers are flexed and the wrist and shoulder may also be flexed and the elbow rotated inward
(J:24743)
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• homozygotes with bilateral forelimb abnormalities have a difficult time from a very young age in moving around the cage and slither around the cage on the undersurface of their muzzles
• develop a more pronounced waddle as grow older
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• maternal abilities are rarely good in females with severe forelimb abnormalities
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• males breed poorly, however females are able to breed successfully
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skeleton
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• radii are thinner and somewhat straighter than in controls, however gross bony landmarks and sections through bones and joints appear normal
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• ulnae are thinner and somewhat straighter than in controls
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muscle
| N |
• do not exhibit any histological abnormalities in skeletal muscle or any reductions in large limb muscle mass
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