Fig. 5. Abnormal layer formation of the olfactory bulb in Fez-deficient mice. (A-T) Coronal sections of the olfactory bulb (A-D,I-T) or olfactory epithelium (E-H) from E18.5 wild-type (WT) and Fez-deficient (Fez^–/–) embryos were analyzed by immunohistochemistry with anti-GAP43, anti-OMP, anti-NCAM, or a combination of anti-reelin and anti-TBX21 antibodies, or by in situ hybridization with reelin, Dlx1, Gad67 and tyrosine hydroxylase (Th) probes. Medial is to the right. Immune complexes were visualized with DAB (A-H), or Alexa488 (anti-reelin) and Alexa568 (anti-TBX21, M,N). In situ signals were stained with BM purple substrate. GAP43 and OMP were expressed in OSNs and in the olfactory nerve layer (ONL) in the wild-type bulb. (A-F) GAP43- and OMP-positive OSNs did not extend after the lamina cribrosa and formed the FCM in Fez-deficient embryos. The expression of GAP43 and OMP in the nasal epithelium was not affected in Fez-deficient embryos. Fez-deficient embryos showed an aberrantly wide mitral cell layer, which expresses reelin and TBX21 (K-N), and displayed a reduced number local circuit neurons, which express Gad67 and Th (Q-T), with aberrant positioning. Periglomerular cells and granule cells are marked by arrowheads and arrows, respectively (Q,S). (O,P) Progenitors for local circuit neurons were located in the ventricular/subventricular zone (VZ/SVZ) and expressed Dlx1; the number of Dlx1-expressing cells was reduced in the olfactory bulb of Fez-deficient embryos.