Methacrylate-embedded E17 embryo (posterior coronal)
Figure 71. This is a slice from the same specimen in Figure 70 cut farther back into the olfactory peduncle where the lumen of the olfactory recess of the lateral ventricle is visible. Similar laminar features seen in Figure 70 are in the medially-placed MOB, but a dorsal area shows a different layering pattern. The dashed-line outline surrounds the settling AOB output neurons. The pars externa of the anterior olfactory nucleus may be on either side of the AOB. Olfactory nerve fibers coalesce into a thick layer surrounding the ventral and medial part of the olfactory peduncle; some fibers are growing through the dense cells beneath the bulb that are forming the cribriform plate of the ethmoid bone. Individual olfactory nerve bundles are plentiful at the periphery of the olfactory epithelium. The two sets of mitotic cells are easily distinguished in this slice as well as the one in Figure 70. Jacobson’s organ is completely separated from the rest of the nasal cavity in this slice, occupying a distinct medial location near the base of the nasal septum. Fascicles of the vomeronasal nerve are in the superficial sensory epithelium and on either side of the nasal septum.