Fig. 1. Laminin (Lm) and -dystroglycan (DG) in normal skeletal muscle. (a-d) Confocal immunofluorescence images of the surface of normal teased muscle fibers immunostained with laminin 2-G domain (a, FITC secondary, green) and -dystroglycan (b, IIH6, Cy3, red) antibodies (a-c, fixed and detergent treated). Laminin and dystroglycan striated patterns colocalize (arrows in a), with less intense laminin fluorescence between striations. (d) Similar fiber image with laminin-dystroglycan costained fiber treated with detergent following laminin immunostaining. (e-h) Peripheral nuclei (e, laminin; f, laminin (green) and -actinin (red); g, oblique optical section showing nucleus protruding beyond plane of sarcolemma (dystroglycan, red; -actinin, green); h, laminin, green; propidium iodide, red). Peripheral nuclei are sandwiched between -actinin of the sarcomere (which coincides with the major costameric circumferential striations) and plasma membrane dystroglycan. (i-j) Periodicity of orthogonally oriented longitudinal optical sections (i, confocal image, laminin-2/4 above and -dystroglycan below; j, deconvoluted widefield image, laminin 2G above and dystroglycan below) of normal fibers. Arrows indicate positions of Z-discs. (k-o) Widefield images reveal repeating pattern of laminin 2G epitope on internal (k,l) and external (m,n) basement membrane surfaces. (k) An oblique view of an internal basement membrane lying between adjacent fibers contained within a computed three-dimensional pixel (voxel) array prepared from 0.25 µm serial deconvoluted optical sections. (l) Location of internal basement membranes within optical cross-section through three adjacent fibers (arrows). (m-o) Images of fixed teased fiber prepared without detergent and stained with laminin 2G-specific antibody following (m) and before (n) deconvolution, and incubated only with secondary antibody (o). Costameric elements (Z, M, L striations) and location of peripheral nucleus (n) indicated in m.