Methacrylate-embedded E20 embryo in the horizontal plane (intermediate)
Figure 117 is an intermediate slice through the MOB in the same specimen as Figure 116 that cuts the olfactory recess—note the cells in the ventricular lumen that must have ruptured from the olfactory NEP or SVZ. The lateral migratory stream of mitral cells is prominent; spindle-shaped cells exit the lateral olfactory tract to migrate into the internal plexiform layer. This slice has well-defined layering—the mitral cell layer is sandwiched between the cell-sparse external plexiform layer and the internal plexiform layer is continuous posteromedially and posterolaterally, and clumps are only apparent in the anterior curve. The presumptive anterior olfactory nucleus and the primary olfactory cortex are farther back.