FIG. 2.

Demonstration of expression of a human CEACAM1 homologue by chinchilla respiratory tract epithelial cells, using immunohistochemistry (A and B) and fluorescence microscopy (C and D). Polarized CMEE cells are depicted in panels A and B, wherein positive labeling for CEACAM1 is depicted by dark brown staining. Serial cross sections of whole frozen chinchilla Eustachian tubes are shown in panels C and D, wherein positive labeling is shown by bright fluorescence at the mucosal surface of the Eustachian tube section shown in panel D. For panels B and C, mouse IgG and FITC-conjugated mouse IgG were used as isotype controls for the similarly unconjugated and FITC-conjugated murine monoclonal anti-human CEACAM1-specific antisera used as the primary antibodies in panels A and D, respectively. Bars, 5 μm (A and B) and 20 μm (C and D).