title: I-bands of striated muscle contain lateral struts.
abstract: In electron micrographs of striated muscle, the I-band often shows a distinct cross-striation. The periodicity of this striation is near 40 nm and has been attributed to troponin, which is localized along the thin filament. However, the cross-striation is often so prominent as to be suggestive of physical structures running transversely across the I-band. We examined I-band ultrastructure using three independent methods: thin sections of chemically fixed specimens; freeze-fracture; and freeze-substitution. With all three methods we found transverse structures distributed throughout the I-band, many of which bridged the gap between neighboring filaments. Such structures were observed in each of the several species studied. In fish muscle in particular, which has a highly regular lattice, it was obvious that these structures gave rise to the observed periodicity.
authors.affiliation: Center for Bioengineering, University of Washington, Seattle 98195.
authors.forename: K
authors.initials: K
authors.lastname: Trombitás
authors.forename: P H
authors.initials: PH
authors.lastname: Baatsen
authors.forename: G H
authors.initials: GH
authors.lastname: Pollack
mesh_terms: D000818:Animals; D001516:Bees; D005399:Fishes; D005404:Fixatives; D005614:Freeze Fracturing; D005615:Freezing; D007313:Insecta; D007365:Intercellular Junctions / Q000502:physiology / Q000648:ultrastructure*; D008854:Microscopy, Electron / Q000379:methods; D009132:Muscles / Q000502:physiology / Q000648:ultrastructure*; D011896:Rana temporaria; D013045:Species Specificity
chemical_list: D005404:Fixatives