Figure 4

GFP expression in OECs from Wnt1-Cre/Floxed-EGFP mice. a, Anti-GFP DAB-nickel-staining of the olfactory system reveals GFP expression in areas populated by OECs. The white arrow indicates the olfactory nerve traversing the cribriform plate from the olfactory mucosa to the olfactory bulb. The white arrowhead indicates the outer layer of the olfactory bulb with GFP⁺ cells. Note that the skeletal system and the meninges, which are derived from the neural crest, are also positive for GFP. The yellow asterisk indicates the area observed in d-f, which corresponds to the groove in the cribriform plate where the olfactory nerves pass before crossing the cribriform plate and the black asterisks indicate the nasal cavity. b-c, Confocal images of the olfactory system showing direct GFP fluorescence and immunostaining for βIII-tubulin. The arrow indicates the olfactory nerve passing through the cribriform plate and the arrowhead indicates the outer layer of the olfactory bulb with GFP⁺ cells. d-f, Cross-section images of the olfactory nerve before it passes through the cribriform plate, displayed as Z-stack confocal images with corresponding x- and y-axes, showing GFP fluorescence and immunostaining for OEC markers p75 (d), GFAP (e), and S100β (f). All images are oriented with the olfactory mucosa above and the olfactory bulb below the shown area. g, Primary OEC cells cultured from the olfactory mucosa and verified by multiple OEC markers were positive for GFP, verifying their neural crest origin. h-i, Venus fluorescence in Sox10-Venus mice verifies the expression of Sox10, a neural crest marker, in OECs at E14.5 (h) and E15.5 (i) The asterisk indicates the nasal cavity. OE: olfactory epithelium, LP: lamina propria, OB: olfactory bulb, NS: nasal septum, CP: cribriform plate. Scale bars: (a, h, i) 200 μm, (b, c) 100 μm, (d-g) 50 μm.