Histochemical and morphological study of dystrophic ( C57BL 6J dy^2J dy^2J) and normal muscle

Morphological and histochemical techniques were utilized to study the soleus and gastrocnemius muscles of normal ( C57BL 6J +/+) and dystrophic ( C57BL 6J dy^2J dy^2J) mice. This is the first such histochemical study of dy^2J dy^2J muscle. The use of the succinic dehydrogenase and acid-stable and alkali-stable adenosine triphosphatase reactions revealed that the dystrophic soleus muscles exhibited decreased numbers of intermediate type fibers, variable numbers of red type fibers, and increased numbers of "abnormal" type fibers compared to normal soleus muscles. The dystrophic intermediate fibers were hypertrophied, the red fibers tended to remain unchanged, and the abnormal fibers were atrophied in comparison to the normal muscle fibers. The dy^2J dy^2J gastrocnemius, unlike the soleus, was preferentially more severely "dystrophic" in one region (red) of the muscle than another (white). The altered histochemical staining of the superficial white region of the dy^2J dy^2J gastrocnemius resulted in a sharp decrease (13% to 16%) in the number of white fibers in a region almost 100% white in the normal animal. There is a possibility that indirect effects (i.e., altered functional demands) of the disease are responsible for the observed histochemical and morphological changes in the dystrophic muscle fibers.