Slices were incubated in GMEM medium containing pCMV-EGFP retrovirus (1 to 5.105 pi/ml), for 2 to 3 hr at 37°C. Slices were then mounted on on laminin/poly-lysine-coated 0.4 μm Millicell culture inserts in a drop of type I collagen and cultured at

37°C, 7.5% CO2, in 6-well plates in GMEM supplemented with 1% sodium pyruvate, 7.2 μM beta-mercaptoethanol, 1% nonessential amino acids, 2 mM glutamine, 1% penicillin/streptomycin, and 10% click here FCS. Primary antibodies used were rabbit anti-Ki67 (Neomarker, 1:400), rabbit anti-Ki67 FITC conjugated (Neomarker, 1:100), mouse anti-NeuN (Milipore 1/100), mouse anti-Pax6 (DSHB, 1/1,000), rabbit anti-Tbr2 (Abcam 1/4,000), sheep anti-EOMES (R&D 1:800), chicken anti-GFP (Invitrogen, 1:1,000), rabbit anti-Geminin (Santa-Cruz, 1:400), and mouse anti-PCNA (Dako, 1/100). We performed 6,003.3 hr (i.e., ∼250 days) of recording in this study. Images were taken every 1 to 1.5 hr for up to 15 days. A cell was considered proliferative if it underwent division during the recording period. DNA Synthesis inhibitor It was designated as a neuron if it started radial migration

with typical migrating neuron morphology or when it was observed nondividing for a duration exceeding 1.5 times the average cell-cycle length of the zone and age under consideration (E48 > 67 hr, E65 > 101 hr and 108 hr, at E78 > 69 hr and 74 hr in the VZ and OSVZ, respectively). We examined 1,071 cells (56 cells at E48; 50 at E67; 71 at E75, two hemispheres; 335 at E65; 559 at E78, four hemispheres). We analyzed 487 divisions (22 at E48; 142 at E65; 31 at E67; 45 at E75; 247 at E78). Quantitative data are presented as the mean ± SEM from representative experiments. Statistical

analyses were performed using the R software. The tests and the corresponding p values are indicated in the out figure legends. For data involving proportions of small number of data points, the Fisher’s exact test was used. Nonparametric statistical tests were preferred because the data did not follow a normal distribution. Wilcoxon test was performed for mean comparison, Kruskal-Wallis test for one-way ANOVA. p < 0.05 was considered statistically significant. The hierarchical clustering (Figure 1J) was performed using the factoMineR package of R (Lê et al., 2008). We thank K. Knoblauch for invaluable and expert guidance in R statistics. We are grateful to M. Valdebenito, M. Seon, F. Piollat, and B. Beneyton for excellent animal care. We are indebted to N. Doerflinger, S. Zouaoui, P. Misery, and C. Lamy for technical assistance and to P. Giroud and J.P. Laigneau for help with the iconography. Administrative and logistic support from C. Nay, N. Kolomitre, and J. Beneyton is acknowledged.