Figure 8.

Immunoelectron microscopic analyses show two apparent pools of label at the plasma membrane of muscle fibers (A) labeling associated with the electron dense plasmalemmal cytoskeleton is seen (arrows) as well as within the cytoplasm adjacent to the plasmalemma (arrowheads). The plasmalemmal labeling is also apparent at the Z-line (B, arrow). However, in this image, it is also clear that the label associated with the Z-line persists right up to the plasma membrane (arrowhead). Labeling of the Z-line is also detected within fibers away from the plasma membrane, as shown in C. In this figure, the label can be seen to be associated with the lateral aspect of the Z-line (arrows) although occasional label within the Z-line is also apparent (arrowhead).