Timing and tempo of generation of corticospinal neurons. A, Developmental changes of the radial position of FG neurons born on E13.5, E15.5, and E16 with respect to corticospinal neurons. Small ×: retrogradely labeled CSNs; red dots, FG neurons; red stars, DLNs (i.e., corticospinal–FG neurons). B, C, Cumulative representation of the generation rate (DLN/CSN) where the cumulated number of DLN produced during the period of corticospinal neurons production divided by the total number of corticospinal neurons is taken as 100%. This measure provides a temporal description of corticospinal neuron production in normal (B) and reeler(C). D, E, Comparison of percentages of DLN/CSN in reeler and normal in area 6 (D) and area 3 (E). Statistical analysis: *p < 0.05, **p < 0.01, according to a χ2analysis. PS, Pial surface; WM, white matter/gray matter limit. Scale bar, 500 μm.