Fig. 4. Defects in the axonal tracts of olfactory sensory neurons in Fez-deficient mice. (A-F) Coronal sections of the frontal region, including the nasal epithelium and anterior telencephalon, of E12.5 wild-type (WT; A,C,E) and Fez-deficient (Fez^–/–; B,D,F) embryos were stained with Hematoxylin and Eosin (HE; A,B), and analyzed by immunohistochemistry with anti-NCAM (C,D) or anti-GAP43 (E,F) antibodies. Immune complexes were visualized by FAST 3,3'-diaminobenzidine (DAB); medial to the right. The axons of OSNs, which express NCAM and GAP43, reached the olfactory bulb in wild-type embryos, but did not extend and generated a fibrocellular mass in Fez-deficient embryos.