Fig 2: ApoE deficiency leads to a decrease in overall proliferation, the number of type 1 NSPCs, and type 1 NSPC proliferation in the dentate gyrus, while leaving the ability of newborn cells to survive and differentiate into granular neurons unimpaired. A–C, Unbiased stereological quantification of the number of BrdU-positive cells (A), the number of BrdU-Prox1 double-positive cells (B), and the percentage of BrdU-positive cells that also express Prox1 (C). D–K, Representative confocal images of the SGZ in WT and ApoE-deficient mice illustrate nestin-expressing (green), Ki67-expressing (red), and GFAP-expressing (blue) cells, along with a merged image of all channels. White arrows indicate nestin-Ki67-GFAP triple-positive cells, representing actively proliferating type 1 NSPCs. L–N, Unbiased stereological quantification of the number of Ki67-positive cells (L), the number of nestin-GFAP double-positive cells (M), and the number of nestin-GFAP-Ki67 triple-positive cells (N). Results are expressed as the mean ± SEM. Unpaired Student’s t tests, *p < 0.05. Scale bar, K, 50 µm.

Fig 3: Type 1 NSPCs express nestin, ApoE, and GFAP, while mature granule cells make connections with astrocytes expressing ApoE and GFAP. A–D, Representative confocal images of the dentate gyrus illustrate nestin-expressing (red), ApoE-expressing (green), and GFAP-expressing (blue) cells, along with a merged image of all channels. E–H, High-power representative confocal images taken from the region in the inset in D illustrate nestin-expressing (red), ApoE-expressing (green), and GFAP-expressing (blue) cells, along with a merged image of all channels. White arrows indicate nestin-ApoE-GFAP triple-positive cells, representing type 1 NSPCs. I–L, Representative confocal images of the dentate gyrus illustrate tdTomato-expressing (red), ApoE-expressing (green), and GFAP-expressing (blue) cells, along with a merged image of all channels. M–P, High-power representative confocal images taken from the region in the inset in L illustrate tdTomato-expressing (red), ApoE-expressing (green), and GFAP-expressing (blue) cells, along with a merged image of all channels. White arrows indicate GFAP and ApoE coexpressing astrocytes. GL, Granule layer; HIL, hilus. Scale bars: D, 100 µm; H, 75 µm; L, 100 µm; P, 25 µm.