Key points are not available for this paper at this time.
Rest and equilibrium length muscle sarcomeres are composed of thin filaments (actin) which traverse the sarcomeres from the Z membranes up to the H band; at this level the filaments are considerably thicker and less numerous. 2. Shortening of muscle is associated with a transformation of thin into thick filaments in the A band. 3. These observations are discussed in terms of interaction of actin and myosin to form a supercoiled structure as the basis of contraction.
David Spiro (Wed,) studied this question.