Methacrylate-embedded E17 embryo (intermediate horizontal)
Figure 68 is a slightly more ventral slice through the evaginating olfactory bulb in the same specimen as in Figure 67. The lateral migratory stream of mitral cells is even more prominent than in Figure 67; spindle-shaped cells exit the lateral olfactory tract to migrate into the external plexiform layer where they peel off to join clumps of settling mitral cells. Note that some of the mitral cells stream into the layer on the medial side, but the next slice (Fig. 69) will show that these cells enter the layer coming from a lateral position on the ventral surface of the bulb. This slice has similar features as the one in Figure 67—the primary olfactory cortex is there, the anterior olfactory nucleus is differentiating between the lateral olfactory tract and the anterior commissure.