Desmosomal Molecules In and Out of Adhering Junctions: Normal and Diseased States of Epidermal, Cardiac and Mesenchymally Derived Cells

Figure 5

Immunoelectron microscopy of ultrathin sections through bovine myocardium (a) and Purkinje fibers ((b)–(d)) using antibodies against desmoplakin. (a) Immunogold labeling of a typical extended area composita structure in an intercalated disk (ID) of adult cardiomyocytes. (b) By contrast, note the relatively small desmoplakin-positive junctions that connect cells of the Purkinje fiber conductive system ((d), desmosomes; arrowheads denote some particularly small desmosome-like junction structures with asymmetric labeling). The desmoplakin-rich plaques of such junctions are very intensely labeled. (c) The morphology and the relatively close packing of the major type of junctions are similar to those of the area composita structures of adult mammalian cardiomyocytes. (d) High-magnification immunoelectron micrograph of a composite junction. Note the very close near parallel association of intermediate-sized filaments (some are denoted by arrows) with junctional plaques. Bars in (a) and (b): 1 𝜇m; bar in (c): 0.25 𝜇m.