Fig. 9. Fez is required in olfactory sensory neurons for axon targeting and OB layer formation. (A-I) The OMP protein (A-C), and the reelin (D-F) and Gad67 (G-I) transcripts in control (WT) and Fez-deficient (Fez^–/–) mice, and in Fez-deficient mice in which Fez expression was rescued under the control of the olfactory sensory neuron-specific #123 promoter (Fez^–/–, Tg+), at postnatal day 0 (P0) were detected by immunohistochemistry or in situ hybridization. Fez^+/– mice containing a transgene composed of #123 promoter-linked Fez-IRES GapVenus expression units [Fez^+/–,Tg(#123p-Fez)] were crossed with Fez^+/– mice to generate control mice (WT), Fez-deficient mice (Fez^–/–) and rescued Fez-deficient mice (Fez^–/–, Tg+). In some of the rescued Fez-deficient embryos, formation of the ONL (OMP-positive, C), the mitral/tufted cell layer (MCL, reelin-positive, F), and the layer of local circuit neurons (glomerular layer, GL; granule cell layer, GCL) was rescued in one or both bulbs. Three different transgenic alleles were used. The numbers of rescued and non-rescued embryos are shown in Table 1. (J) Transgene-mediated Fez expression in the olfactory epithelium (OE), but not the olfactory bulbs (OB), of Fez^–/– mice partially rescued axon projection (arrowhead) of OSNs at E14.5. The OSNs expressing the transgene were monitored by immunohistochemistry with an anti-GFP (anti-Venus) antibody.