Toluidine blue staining of respiratory nasal epithelia of rabbit fetuses exposed to P. multocida. (a) Normal epithelium not exposed to bacteria or lectins; LM, scale bar = 20 μm. (b-c) Nasal septa of positive control tissues exposed only to P. multocida. (b) P. multocida adhering to cilia (arrow); LM, scale bar = 10 μm. (c) GCs showing increased numbers and excretory activity. All of the GCs are protruding above the apical limit of their neighboring cells and liberating their contents (arrows); LM, scale bar = 10 μm. (d) Nasal epithelium exposed to both bacteria and PNA. The lectin inhibited the increase in the number of GCs, though some loss of cilia can still be observed; LM, scale bar = 10 μm.