Schema of the changing distribution of newborn neurons over time. At week 1, BrdU-labeled cells are nestled on the medial and lateral sides of the olfactory (OL) and accessory (AL) lobes, near the proliferation zones of cell clusters 9 and 10. By week 14, BrdU-labeled cells are found throughout the dorsal-ventral extent of clusters 9 and 10, and cells have dispersed from the sites where they proliferated. Dorsally, cluster 9 cells occupy a small region, while more ventrally these are distributed throughout the cluster. BrdU-labeled cells occupy positions at the rostral and caudal ends of cluster 10 dorsally, while ventrally the labeled cells are found in the lateral margins of the soma cluster.