Optical diffraction of the Z lattice in canine cardiac muscle.

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Abstract
Optical diffraction patterns from electron micrographs of longitudinal and cross sections of normal and anomalous canine cardiac Z bands were compared. Anomalous cardiac Z bands resembling nemaline rods are structurally related to Z bands in showing a repeating lattice common to both. In thin sections transverse to the myofibril axis, electron micrographs and optical diffraction patterns of the Z structure reveal a square lattice of 24 nm. This lattice is simple at the edge of each I band and centered in the interior of the Z band, where 2 distinct lattice forms were observed. In longitudinal sections, oblique filaments visible in the electron micrographs correspond to a 38 nm axial periodicity in diffraction patterns of Z band and Z rod. The Z rods will be useful for further analysis and reconstruction of the Z lattice by optical diffraction techniques.