FIG. 3. Immunohistochemical characterization of epithelial cells. Alveoli in mouse (A) and bat (B) glands are surrounded by a layer of myoepithelial cells (arrow) that express keratin 5 (brown stain). Nuclear localization of Stat5a (green) can be seen in both mouse (C) and bat (D) epithelial cells. Npt2b, a transporter protein, is localized on the apical membrane (red) of both mouse (E) and bat (F) secretory epithelial cells. E-cadherin is visible in the plasma membrane of mouse (red in C and green in E) and bat (red in D and green in F) epithelial cells. C' through F' are negative controls stained with omission of the primary antibodies to demonstrate staining specificity. Bar = 20 µm (A and B) and 16 µm (C–F)