Fig. 8. L-glutamine stimulates a significant increase in activity-dependent labeling of the zebrafish olfactory epithelium compared to agmatine (AGB) control preparations, but the polyamine stimuli do not. The olfactory epithelium was stimulated with (A) 5 mmol l^–1 AGB, (B) 5 mmol l^–1 AGB + 100 µmol l^–1 spermine, (C) 5 mmol l^–1 AGB + 100 µmol l^–1 putrescine or (D) 5 mmol l^–1 AGB + 100 µmol l^–1 L-glutamine. In all preparations the labeling is largely restricted to cells within the sensory epithelium. In all panels the midline raphe (R) is located on the right and non-sensory epithelium can be seen on the left end of the lamellae (L). Scale bar, 10 µm.