Skeletonized reconstructions of the basal dendritic trees of pyramidal cells (in the tangential plane) sampled from the primary visual (V1), inferotemporal visual association (TE), and granular prefrontal (PFC) cortex at 2 d postnatal (2D), 3.5 months postnatal (3½M), and 4.5 years postnatal (4½Y). The illustrated cells represent the average of all cells sampled for each cortical area/age group. Insets illustrate the spine density for cells of each cortical area/age group at 50–70 μm from the cell body.