Methacrylate-embedded E14 embryo (dorsal horizontal)
Figure 20 is the most dorsal slice through the olfactory epithelium—the lower half of the slice has a sliver of the nasal cavity. The olfactory nerve is probably associated with the dense clump of cells extending from the olfactory epithelium to the brain. The presumptive vomeronasal nerve is in three discrete bundles. The NEP is sliced tangentially in the basal forebrain and appears very thick. The presumptive olfactory NEP is between the presumed septal NEP and the massive eminence protruding into the lateral ventricle in the basal telencephalic and basal ganglionic NEP. It is important to note that migrating cells are not prominent in this slice. The solid-line arrows indicate a few spindle shaped neurons that may be migrating forward toward the part of the brain that will evaginate as the olfactory bulb. The dashed-line arrow indicates a possible migratory trajectory for the accessory olfactory bulb output neurons. It is also possible that some AOB output neurons may migrate forward from germinal sources in the basal telencephalic NEP. Generally, most cells appear to be migrating radially from the septal and olfactory NEPs.