Depletion of slowly dividing neural stem cells in the Rbpj-mutant adult brain. A, Experimental design. B–M, Dividing progenitors (t = 0; B–D, H–J) and slowly dividing cells, ones that retained labeling even after 12 d (t = 12; E–G, K–M), were labeled with BrdU in control (B–G) and Rbpj-mutant (H–M) mice.