3H-thymidine injections from E15 to E16 and survival to postnatal day (P)5 (posterior)
Figure 27 is a slice from the same specimen that cuts through the accessory olfactory bulb (AOB) dorsally, the main olfactory bulb (MOB) medially, and the anterolateral part of the anterior olfactory nucleus. Like the P21 survival specimen in Figure 25, labeling patterns in the AOB and MOB show many unlabeled AOB output neurons, densely labeled AOB granule cells that stand out, many heavily-labeled MOB mitral cells and light-to-unlabeled granule cells in the MOB (due to label dilution). On the morning of E15, the AOB output neurons and large cells in the internal and external plexiform layers have nearly all been generated. In the MOB, virtually all cell populations have actively proliferating precursor cells in their respective germinal zones. There are several heavily labeled cells in the superficial anterior olfactory nucleus, while more lightly labeled cells are deep—exactly the opposite of the deep-to-superficial cortical gradient.