Analysis Tools
immune system
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• at 3 months of age, the diaphragm shows multiple endomysial foci of mononuclear inflammatory cells
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• at 3 months of age, quadriceps show multiple endomysial foci of mononuclear inflammatory cells
• however, at 6 months, endomysial inflammation is reduced in quadriceps and only scattered inflammatory cells are present
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muscle
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• conspicuous necrosis and regeneration at 3 weeks of age
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• scattered foci of necrotizing fibers surrounded by cellular infiltration can be found in soleus and plantaris muscles as early as 14 days of age, and subsequently in the tibialis anterior, and lastly the extensor digitorum longus with foci of basophilic myotubes being found from 4 weeks of age on
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• at 3 months of age, the diaphragm shows multiple endomysial foci of mononuclear inflammatory cells
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• at 3 months of age, quadriceps show multiple endomysial foci of mononuclear inflammatory cells
• however, at 6 months, endomysial inflammation is reduced in quadriceps and only scattered inflammatory cells are present
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• the extensor digitorum longus, but not the soleus, at 32 weeks of age has a greater proportion of fast-twitch-oxidative-glycolytic fibers and a smaller proportion of fast-twitch-glycolytic fibers than controls
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• although the number of fibers is normal, the cross-sectional area of the fibers of the tibialis anterior is larger than normal at 3 and 6 months of age
(J:19034)
• at 32 weeks of age in the soleus fast-twitch-oxidative-glycolytic fibers have a larger cross-sectional area than those of controls
(J:152749)
• at 32 weeks of age in the extensor digitorum longus muscle both the slow-twitch-oxidative and fast-twitch-glycolytic fibers have a larger cross-sectional area than those of controls
(J:152749)
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• peripherally nucleated fibers replace the normal fibers in the tibialis anterior, extensor digitorum longus, plantaris, and soleus in a progressive manner, reaching a plateau of 80-90% of fibers at 26 weeks of age
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• elevated hydroxyproline in the diaphragm at 24 weeks of age but not at 3 weeks of age
(J:95776)
• unlike skeletal muscle, the diaphragm undergoes progressive degeneration without regeneration such that, although at 30 days of age foci of myofiber degeneration, necrosis, mineralization, and regeneration are present but not extensive, at 6 months of age the diaphragm has a wide variation in myofiber size and architecture, continued necrosis and connective tissue proliferation, and at 16 months of age the diaphragm is pale due to the extensive myofiber loss and replacement fibrosis and the remaining fibers are ensheathed in dense collagenous tissue with most having architectural aberrations
(J:152891)
• at 16 months of age there are twice normal levels of slow myosin in the diaphragm, a decrease in isometric force generation, and a shortened fiber length
(J:152891)
• at 1.5 years of age the diaphragm is found to have significantly reduced passive stretch capacity although overt respiratory compromise is not found in aging mutants
(J:152891)
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• the anterior scalene and intercostal muscles at 1 to 1.5 years of age have dystrophic changes similar to those of the diaphragm at 6 months of age
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• the cross-sectional area and wet weight of the tibialis anterior is greater than normal by 10 weeks of age
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• detectable up to 12 months of age but not at 15 months of age, at which point muscle fibers appear atrophied and extensively split
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• found with age in the soleus and plantaris
(J:19034)
• mice develop progressive endomysial fibrosis with increased collagen III deposition in the diaphragm
(J:140282)
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• at 23 degrees hemidiaphragm preparations show lower than normal resting membrane potentials and insertion of a glass microelectrode into a single muscle fiber results in repetitive bursts of muscle action potentials in 30 to 50% of fibers, while at 37 degrees only 7.8% of muscle fibers display this electrical myotonia and the resting membrane potentials are normal
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• at 4 weeks of age the soleus muscle has decreased twitch and tetanus tension compared with controls, but this is normal by 32 weeks of age
• at 3 and 32 weeks of age the extensor digitorum longus muscle has decreased twitch and tetanus tension and faster time-to-peak twitch tension compared with controls and the maximum velocity of unloaded shortening is also decreased at 32 weeks of age
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vision/eye
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• hemizygous males between 20 and 24 weeks of age have normal ERG readings even though abnormal b-waves are often found in Duchenne Muscular Dystrophy patients and are found in the mdx-3cv hemizygotes
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• nuclear opacity of the lens is found at 1 day of age
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• a slight anterior subcapsular opacity is seen at 4 days of age, which spreads anteriorly such that at 150 days of age there is complete anterior subcapsular opacity in addition to the nuclear opacity
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nervous system
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• at 8 weeks of age miniature endplate potential frequency, the quantal content of endplate potentials, the amplitude and time course of miniature endplate currents, and the number of acetylcholine receptors at the postsynaptic membrane are all normal
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• although the nerve terminal innervation of epitronchleoanoconeus muscle is normal, the terminal architecture of regenerated muscle fibers, those with central nuclei, are more complex than normal with an increase in the number of fine terminal arborizations, many of which have bouton-like swellings and, rather than the normal confluent pattern at postsynaptic regions, staining of acetylcholine receptors is found in numerous small spots corresponding to the boutons on the motor axon terminals with acetylcholinesterase staining in close association
• electron microscopy shows that neuromuscular junction postsynaptic membranes are variably simplified with a reduction in the number of secondary synaptic folds
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cellular
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• conspicuous necrosis and regeneration at 3 weeks of age
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• scattered foci of necrotizing fibers surrounded by cellular infiltration can be found in soleus and plantaris muscles as early as 14 days of age, and subsequently in the tibialis anterior, and lastly the extensor digitorum longus with foci of basophilic myotubes being found from 4 weeks of age on
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