Methacrylate-embedded E18 embryo (ventral horizontal)
Figure 86. This ventral horizontal slice from the same specimen in Figures 84 and 85 clearly shows the fan-like array of migrating mitral cells in the tangentially cut internal plexiform layer. Mitral cells leave their axons behind in the lateral olfactory tract and head toward the mitral cell layer that occupies the lateral, anterior, and medial edges of the bulb, beneath the cell-sparse external plexiform layer (solid-line curved arrows). The anterior olfactory nucleus is tentatively identified in the olfactory peduncle in front of the primary olfactory cortex on the lateral side of the brain. Migrating cells stretching across the peduncle can go in either direction, some medial, others lateral (double-ended curved arrow).