Figure 4.

Frzb deletion seems to affect development of the olfactory nerve layer. Coronal sections through the mouse olfactory system at E16.5, immunostained for the maturation marker Omp, the outer ONL marker peripherin (Prph), and the general axonal marker Tubb3. (a–c²) In a heterozygous Frzb ^+/− embryo, Omp immunoreactivity labels the olfactory nerve, the full width of the ONL, and many olfactory receptor neurons in the olfactory epithelium, while peripherin immunoreactivity labels the olfactory nerve and the outer ONL. Some peripherin‐positive, Omp‐negative axons are also seen deep to the ONL, in the external plexiform layer (arrowheads, c–c²). (d–f²) In a Frzb‐null embryo, the Omp‐immunoreactive ONL seems to be thinner, and peripherin immunoreactivity is not detectable in the external plexiform layer. EPL, external plexiform layer; OB, olfactory bulb; OE, olfactory epithelium; ON, olfactory nerve; ONL, olfactory nerve layer. Scale bar: 50 μm (a,b,d,e) and 25 μm (c,f) [Color figure can be viewed at wileyonlinelibrary.com]