Zebrafish olfactory epithelium. A: Arginine. The image is marked to indicate the main features of the OE; arrowhead indicates the beginning of non-sensory epithelium. The AOI mask is overlaid and color-coded (see legend in Fig. 3) by class: 1, blue; 2, yellow; 3, red; 4, green; 5, cyan; 7, purple (Classes 6 and 8 see Fig. S3). B: Aspartate. C: Glutamate. D: Glycine. E: GSH. F: Taurine. G-H: RGB images of the zebrafish OE. I: Higher magnification image of area within white dashed line in G. Numbers, arrows and arrowheads indicate the Class number. BL, basal lamina (dashed line in A). Scale bars: A = 10 μm, I = 5 μm.