By altering the placement of the lead shield, as shown in the Nissl-stained sagittal section in the upper panel, NSC/NPCs can be depleted from the rat hippocampus while being spared in the SVZ. The lower panels show BrdU-immunostained sections (a,c,e,g,i,k; bar = 250µm) from regions of the SVZ and hippocampus of a P30 rat irradiated at P28 (white boxes in the phase contrast images; b,d,f,h,j,l; bar = 500µm) that demonstrate the selective depletion of neural stem/progenitor cells from the hippocampus. (m–o) Targeted hippocampal irradiation at the time of birth (P0) eliminates NSC/NPCs from the hippocampus during the developmental formation of the dentate gyrus (bar = 300µm). Note the conspicuous absence of BrdU+ cells in the irradiated hippocampus (m, red arrow) as compared to the untreated side (n, black arrow).