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D SPIRO

Publications and source records attributed to D SPIRO.

28 records · Page 2Linked to original sources
PubMed1956

The ultrastructure of striated muscle at various sarcomere lengths.

1. 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.

Actins↗
PubMed1954

Electron microscope studies on ultrathin sections of muscle.

Thin sections of striated muscle from frog (sartorius), rabbit (psoas), rat (heart), and fly (flight muscle), and of smooth muscle from clam (adductor) have been obtained using a new microtome. Electron micrographs of them are presented. The sections are sufficiently thin to achieve a resolution of 30 to 40 A. In fly flight muscle, the myofibrils are distinct and well separated morphological units. In frog and rabbit muscle the myofibrils appear to be so closely packed under normal conditions that their identity as separate units is almost lost. In all types of striated muscle examined, it was found that the filaments are arranged within the myofibrils in a continuous and highly regular hexagonal array. The diameter of the filaments in embedded, sectioned muscle appears to be significantly less than that observed in dried shadowed material. The 400 A axial period, observed in frog and rabbit muscle, and in rat heart muscle, was found to extend across the interstitial material between the filaments. The significance of these findings is discussed.

Animals↗