Extended Data Figure 9: Development of the macaque DG and evidence of the presence of a proliferative SGZ and postnatal neurogenesis with a sharp decline in adulthood.

a, The E150 macaque hippocampus has many Ki-67⁺ cells in the SGZ as well as vimentin⁺ fibres and DCX⁺ cells between the dNE and the GCL (arrow). b, Toluidine-blue-stained semi-thin sections of the macaque DG reveal small and dark condensed nuclei (arrows) in the SGZ from fetal ages (E150) to 1.5 years; few are visible in the DG at 7 years of age and these cells are very rare in the DG of a 23-year-old macaque (compare with human data in Extended Data Fig. 2a). c, Profiles of the cellular populations in the macaque DG at 6 months, 1.5, 7 and 23 years of age. As in the human DG, DCX⁺ cells decrease markedly with age and have little cytoplasm and a smaller nucleus compared to mature granule neurons. d, Top, example of a DCX⁺NeuN⁺ cell with mature dendrites in the GCL of a 5-year-old macaque. Middle, bottom, two examples of DCX⁺PSA-NCAM⁺ cells with dendritic arborization present in the GCL of a 7.5-year-old macaque. An axonal extension (arrow) into the hilus is visible. e, The ventricular–subventricular zone (SVZ) and olfactory bulb (OB) of a 23-year-old macaque contain some DCX⁺SP8⁺ cells with the morphology of young neurons, but similar cells are rare in the GCL of the 23-year-old macaque (Fig. 4b, d). f, DCX⁺ cells in the SGZ of a 1.5-year-old macaque express transcription factors in common with those in the mouse SGZ. g, Percentages of DCX⁺ cells expressing markers shown in f. h, Immunostaining images of BrdU⁺ cells and cell proliferation (Ki-67, MCM2), progenitor cell markers (SOX2, ASCL1) or DCX, in the 1.5-year-old macaque euthanized 2 h after BrdU injection. BrdU⁺DCX⁺ and BrdU⁺NeuN⁺ cells could be identified 10 or 15 weeks after BrdU exposure, respectively. i, DAB-staining for BrdU in the ventricular–subventricular zone and SGZ of a 1.5-year-old macaque, 2 h after BrdU injection. j, Example of a rare DCX⁺BrdU⁺ cell in the 7.5-year-old macaque. Scale bars, 1 mm (a (left)) 200 μm (a (right), e (top left, bottom left), i (left)), 100 μm (b (left)), 20 μm (d, e (middle left and right), f, h, i (right), j) and 10 μm (b (right), c).