Ultrastructure of the developing myotendinous junction of genetic dystrophic chickens.

This paper presents an ultrastructural study of the changes occurring within the tendon and at the insertion of the developing gastrocnemius of White Leghorn chickens and the dystrophic lines 413 and 423 from Davis, CA. The study revealed that the Davis lines contained abnormalities in these areas as early as 13 d in ovo with progressive deterioration to 19 d in ovo. The fibroblasts, collagen, and myofibers showed significant alterations as early as 13 in ovo. Fibroblasts contained abnormal mitochondria and altered Golgi bodies. At day 19, many were ruptured. The average diameter of collagen fibrils was smaller in the dystrophic chickens and myofibers showed a variety of alterations, some of which were severe. The details of these alterations are described and their possible relationship with the etiology of genetic muscular dystrophy is discussed.