Methacrylate-embedded E15 embryo (intermediate sagittal)
Figure 34 is an intermediate sagittal slice of the evaginating olfactory bulb in an E15 embryo through lateral Jacobson’s organ; vomeronasal nerve bundles are not in the slice. The olfactory nerve bundles coalesce to form a large contact zone with the anteroventral forebrain where the brain surface blends with the nerve. Arrows indicate young neurons exiting the basal telencephalic and septal NEPs—some appear to turn and migrate toward the olfactory bulb. Probably these are pioneer mitral cells and AOB output neurons that will eventually settle in their respective locations. No laminar differentiation is discernable in the olfactory bulb itself. There is only a thickened layer (compared to the dorsally adjacent neocortical primordium) of differentiating cells accumulating in the olfactory nerve contact zone.