Differentiation in dystrophic muscle cultures from mice of different ages.

Muscle from dystrophic (129 ReJ dy/dy) mice, aged 1, 2, 3, 4, and 6 months, was cocultured with normal embryonic mouse spinal cord. Cultures were scored for regeneration (myotubes) and differentiation (cross-striated or contracting fibers) over a 28-day period. Although muscle from dystrophic mice of all ages was able to regenerate, the ability to differentiate decreased with the increasing age of the mouse. Muscle from litter-mate control mice of different ages regenerated and differentiated equally well.