Glycogen in crustacean fast and slow muscles

Abstract

Ultrastructural examination of crayfish superficial (tonic) and deep (phasic) abdominal extensor muscles reveals a distribution and quantitative difference in glycogen between these muscles. Both superficial and deep fibers have a dense accumulation of glycogen in the interfibrillar sarcoplasm. In addition, the superficial extensors, but not the deep extensors, contain glycogen in the I band region. The glycogen granules are of the β type and can be removed enzymatically. The superficial medial and lateral fibers contain more glycogen than the medial and lateral deep fibers. A possible functional role for this difference is suggested. © 1973 by the American Society of Zoologists.