Fig. 1. Transmission electron micrographs of desmosomes in mouse epidermis. Normal (A) and wound-edge (B) mouse epidermis after exposure to calcium-free Dulbecco's minimum essential medium with 10% chelated foetal bovine serum and 3 mM EGTA (LCM-EGTA) for 6 hours (A) and 1 hour (B). Note that the desmosomes in A are intact and two that are sectioned precisely transversely exhibit midline structure, whereas in B the desmosomal halves (blue arrows) have lost adhesion and separated. Thus the desmosomes in A are calcium independent and those in B are calcium dependent. Quantification is shown in Table 1. (C-F) Comparison between desmosomes in unwounded and wound-edge epidermis. (C) Desmosome in unwounded epidermis showing characteristic midline structure. (D-F) Examples of transversely sectioned desmosomes from wound-edge epidermis showing absence of midlines. Quantification is shown in Table 2. Bars, 0.1 µm.