Spontaneous myopathy in the SJL/J mouse: pathology and strength loss

Muscle Nerve. 1997 Jan;20(1):72-82. doi: 10.1002/(sici)1097-4598(199701)20:1<72::aid-mus10>3.0.co;2-3.


Myopathy has been found to develop spontaneously in 100% of SJL/J mice between 6 and 8 months of age. Extent of muscular involvement and mouse strength were quantified in SJL/J mice and Balb/c control mice 2-16 months old. Muscle from young SJL/J mice exhibited histopathological abnormalities and occasional inflammatory infiltrate. By 6 months, 78% of SJL/J mice had developed active myopathy. By 8 months, all SJL/J mice examined had active disease with a mean of 12.9% of muscle fibers affected. Replacement of muscle fibers by fat and/or collagen began at 10 months and was pronounced by 14 months. Significant decreases in strength scores (total body pulling force) at 6 months and 10 months of age reflected the onset of active myopathy and the onset of muscle degeneration, respectively. The spontaneous onset and 100% incidence of myopathy in the SJL/J mouse line should provide a useful model for idiopathic myopathy.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Age Factors
  • Animals
  • Disease Models, Animal*
  • Female
  • Mice
  • Mice, Inbred BALB C
  • Microscopy, Electron
  • Muscle Fibers, Skeletal / ultrastructure*
  • Myositis / pathology*