Fig. 7. Abnormal projection of olfactory axons in Arx-deficient mice. (A,B) Immunofluorescence labeling of NCAM (red: olfactory axons) and PI staining (blue: nucleus) on parasagittal sections of E12.5 wild-type (A) and Arx-deficient (B) mice. In both mice, pioneer olfactory axons reached the anterior tip of the telencephalon (T). (C,D) Coronal sections of Nissl-stained olfactory epithelium (OE) of E16.5 wild-type (C) and mutant (D) mice. (E,F) Immunohistochemical analysis of olfactory marker protein (OMP) expression in mature olfactory sensory neurons in the OE of E16.5 wild-type (E) and mutant (F) mice. (G,H) Immunofluorescence labeling of OMP (red: olfactory axons) and PI staining (blue: nucleus) on parasagittal sections of the olfactory bulb (OB) from E16.5 wild-type (G) and mutant (H) mice. In mutant mice, a small subpopulation of olfactory nerve (ON) kept contact with the OB (arrowheads in H). However, most of the ON did not reach the OB and terminated in an unusual axon-tangled structure, the FCM, in front of the OB (asterisk in H). Scale bars: in B, 100 µm for A,B; in D, 400 µm for C,D; in F, 600 µm in E,F; in H, 200 µm for G,H.