All animals were sacrificed between 2.5 and 3 months of age, in this species a time when neurons have completed migration to their final areal and laminar positions (Rakic, 1974, 2002c). With and without shrinkage corrections (including normalization of cortical thickness), plotting of the histograms representing the continuous distribution of mean percentage BrdU and 3H-dT cells in bins of 100 μm from pia to (an including) the WM indicated that, for the same injection times and for corresponding cortical areas, the peak accumulation of BrdU and 3H-dT cells do not coincide and BrdU labeled cells are more widely dispersed