(A–C) Schematics of a vertical section of the epidermis before ETA treatment (A), after intradermal injection of ETA (B), and after trypsin treatment (C). Green squares, TJ; red squares, desmosome; SG, stratum granulosum; SC, stratum corneum. Both SC and SG cells are drawn as f-TKD (see Figure 4A–C). (A) TJs are located at the apical edges of the SG2–SG2 cell contact. (B) Desmosomal junctions are digested by ETA beneath the TJ barrier but not above it, as the permeation of ETA is limited at the TJ barrier, and a stratified cell sheet consisting of SC, SG1, and SG2 cells is separated from the skin (Yoshida et al., 2013; Yokouchi et al., 2015). The en face images of the resulting ETA-induced cell sheet are shown in Figure 2A and E. (C) SG1 and SG2 cells are dissociated from the ETA-induced cell sheet by trypsin, as trypsin digests both TJs and desmosomal junctions. ZO-1, the TJ intracellular scaffold protein, remains undigested [green squares in (C)]. The cytosolic portion of Dsg1 also remains undigested in the cytoplasm (not shown). The representative en face images of the isolated SG2 cells are shown in Figure 3F and Video 7. TJ, tight junction.