Comparison of Muscle Tissue from Normal and Dystrophic Chick at Different Stages of Development.

Summary 1. Evidence is presented to support the view that dystrophic muscle is retarded in its post-hatching maturation. DNA, PN, and incorporation levels were determined in developing chick normal and dystrophic pectoralis. By 11 days post-hatching, dystrophic muscle has a higher DNA content, greater incorporation of glycine-1-C14 into protein, and a lower PN content corresponding to the levels found in younger normal muscle. 2. After 5 days in vitro, normal and dystrophic muscle explants from 11-day hatched chick lost DNA and PN. In addition, the rate of protein synthesis was increased. Again, in explants the dystrophic muscle showed properties similar to those of normal muscle of a younger age.