Fig. 2. Inv-Dsg2 mice develop epidermal hyperplasia. Hematoxylin and Eosin staining of newborn back skin (A,B) and adult (C-J) back skin (C,D,I,J), ear (E,F) and tongue (G,H) of wild-type control (A,C,E,G,I) and Inv-Dsg2 transgenic (B,D,F,H,J) littermate mice. Newborn and adult mice were 2 days and 3 months old, respectively. Histological analysis shows varying degrees of epidermal thickening in all Inv-Dsg2 transgenic tissues examined. Minor compaction (B,D; asterisk) and the presence of nuclei (B,D; arrows) was observed in the outermost granular and horny layer interface. A more dramatic difference in epidermal thickness was observed in the adult transgenic mice compared that of control littermates (C,D; brackets) and to newborn transgenic skin. Pink translucent flattened eosinophilic keratinocytes were apparent in the stratum corneum (F; open arrow). Cells and nuclei in the spinous layers of transgenic epithelia appear slightly enlarged relative to those in wild-type epithelia. Bars, 25 µm.