Concomitance of basophilia, ribonucleic acid and acid phosphatase activity in regenerating muscle fibres.

Regenerating fibres from tibialis anterior muscles of mice and hamsters transplanted as minced fragments for 7 and 9 days respectively were compared for basophilia, ribonucleic acid (RNA) and acid phosphatase activity with fibres in muscles of patients with Duchenne muscular dystrophy, limb--girdle dystrophy and dermatomyositis. Normal muscles of mice, hamsters and humans were used as controls. In normal muscle fibres basophilia and RNA activity were restricted to the nuclei and acid phosphatase activity was occasionally observed in the nuclei, endomysial connective tissue and around muscle spindles. Diseased human muscle fibres were rich in acid phosphatase activity, the enzyme being most prominent in degenerating and basophilic fibres. When examined in serial sections, all basophilic fibres showed RNA and acid phosphatase activity. Similarly, all regenerating fibres in minced transplants which were basophilic to haematoxylin contained high RNA and acid phosphatase activity. It is suggested that basophilia in diseased human muscle fibres represents regeneration and that the lysosomes, as defined by acid phosphatase activity in these fibres, may be promoting their growth and differentiation by facilitating greater nucleocytoplasmic communication which ultimately could lead to protein synthesis.