Estimates of adult-born cells in the GCL of female CCK1R−/− and wild-type mice. BrdU (50 mg/kg i.p.) was administered twice daily for 5 consecutive days, and mice killed 42 days after the last BrdU administration (see Protocol 2, Figure ). (A,B) Estimated number of BrdU+ cell bodies in the GCL of wild-type and CCK1R−/− mice (A). Photomicrograph of BrdU+ cell bodies in the GCL of (B) wild-type and (B′) CCK1R−/− mice. (C–E) Estimated number of BrdU+ and GABA-ir double-labeled cell bodies in the GCL of wild-type and CCK1R−/− mice (C). (D) Estimated number of BrdU+/GABA-ir co-expressing cell bodies expressed as a proportion of the total number of BrdU+ cell bodies in the GCL of wild-type and CCK1R−/− mice. (E) Double-immunofluorescence confocal micrograph showing BrdU-LI (E′, red) and GABA-LI (E″, green) in the GCL of CCK1R−/− mouse. (G–I) Estimated number of BrdU+ and NeuN-ir double-labeled cell bodies in the GCL of wild-type and CCK1R−/− mice (G). (H) Estimated number of BrdU+/NeuN-ir co-expressing cell bodies expressed as a proportion of the total number of BrdU+ cell bodies in the GCL of wild-type and CCK1R−/− mice. (I) Double-immunofluorescence confocal micrograph showing BrdU-LI (I′, red) and NeuN-LI (I″, green) in the GCL of CCK1R−/− mouse. (J–L,F) Estimated number of BrdU+ and calretinin-ir double-labeled cell bodies in the GCL of wild-type and CCK1R−/− mice (J). (K) Estimated number of BrdU+/calretinin-ir co-expressing cell bodies expressed as a proportion of the total number of BrdU+ cell bodies in the GCL of wild-type and CCK1R−/− mice. (L) Double-immunofluorescence confocal micrograph showing BrdU-LI (L′, red) and calretinin-LI (L″, green) in the GCL of CCK1R−/− mouse, shown at higher magnification in (F), (F′), and (F″), respectively. In all plots, black bars = female wild-type animals (n = 4), and red bars = female CCK1R−/− mice (n = 4). Arrowheads point to double-labeled cell bodies, and arrows to single labeled BrdU+ cell bodies. BrdU, 5-bromo-2-deoxyuridine; CalR, calretinin; GABA, γ-aminobutyric acid; GCL, granular cell layer of OB; ir, immunoreactive; KO, CCK1R−/−; NeuN, neuronal nuclei; WT, wild-type; +, positive. Scale bars: (B) = 200 μm, applies (B,B′); (E) = 50 μm, applies (E,E′,E″); (F) = 10 μm, applies (F,F′,F″); (I) = 50 μm, applies (I,I′,I″,L,L′,L″).