Fig. 2. Horizontal Z-disk displacement (
xmyo) plotted versus sarcomere length (SL) for extensor digitorum longus fifth toe muscles of wild-type (circles) and desmin-null (squares) animals. Superficial regions are shown with open symbols while deep regions are shown with filled symbols. Note that xmyo increases to a greater extent as SL increases in muscles from knockout compared with wild-type animals. Error bars represent ±1 S.E.M. in either the xmyo or SL direction (N=7 wild-type muscles and N=9 desmin-null muscles). Superficial and deep regions of each muscle were sampled from 10 micrographs per region. The regression slope of the xmyo versus SL relationship was significantly different from zero in the specimens from knockout animals (P<0.005) but not in the specimens from wild-type animals (P>0.4), and analysis of covariance (ANCOVA) revealed a significant difference between the slopes of these relationships (P<0.05).
